config: drop go-toml and the legacy TOML migrations

The one-shot config.toml -> config.ini and books.toml -> books.ini
migrations (a transition aid from the pre-INI format) are removed, along
with the github.com/pelletier/go-toml/v2 dependency and the now-dead
`toml:` struct tags. The live config format has been INI for many
releases; anyone still on a .toml recreates it (the format is
self-documenting on first run). Leaves 3 direct deps, all in active use
(bubbletea, lipgloss, go-pdf/fpdf). Tests updated to write INI.

4 files changed, 40 insertions, 141 deletions

diff --git a/go.mod b/go.mod
index f80d413..e2ba908 100644
--- a/go.mod
+++ b/go.mod
@@ -6,7 +6,6 @@ require (
 	github.com/charmbracelet/bubbletea v1.3.10
 	github.com/charmbracelet/lipgloss v1.1.0
 	github.com/go-pdf/fpdf v0.9.0
-	github.com/pelletier/go-toml/v2 v2.4.2
 )
 
 require (
diff --git a/go.sum b/go.sum
index d57ae4f..8aa8bc9 100644
--- a/go.sum
+++ b/go.sum
@@ -30,8 +30,6 @@ github.com/muesli/cancelreader v0.2.2 h1:3I4Kt4BQjOR54NavqnDogx/MIoWBFa0StPA8ELU
 github.com/muesli/cancelreader v0.2.2/go.mod h1:3XuTXfFS2VjM+HTLZY9Ak0l6eUKfijIfMUZ4EgX0QYo=
 github.com/muesli/termenv v0.16.0 h1:S5AlUN9dENB57rsbnkPyfdGuWIlkmzJjbFf0Tf5FWUc=
 github.com/muesli/termenv v0.16.0/go.mod h1:ZRfOIKPFDYQoDFF4Olj7/QJbW60Ol/kL1pU3VfY/Cnk=
-github.com/pelletier/go-toml/v2 v2.4.2 h1:M2fKKbmyvI+hGId/D0W64qDBMVhJnNR10O5gIbMc//Q=
-github.com/pelletier/go-toml/v2 v2.4.2/go.mod h1:2gIqNv+qfxSVS7cM2xJQKtLSTLUE9V8t9Stt+h56mCY=
 github.com/rivo/uniseg v0.2.0/go.mod h1:J6wj4VEh+S6ZtnVlnTBMWIodfgj8LQOQFoIToxlJtxc=
 github.com/rivo/uniseg v0.4.7 h1:WUdvkW8uEhrYfLC4ZzdpI2ztxP1I582+49Oc5Mq64VQ=
 github.com/rivo/uniseg v0.4.7/go.mod h1:FN3SvrM+Zdj16jyLfmOkMNblXMcoc8DfTHruCPUcx88=
diff --git a/internal/config/config.go b/internal/config/config.go
index 0596194..a225a12 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -2,10 +2,8 @@
 //
 // Resolution order: LECTIO_CONFIG env var -> ~/.config/lectio/config.ini
 // (auto-seeded from the embedded default on first run, honoring
-// XDG_CONFIG_HOME via os.UserConfigDir()) -> built-in defaults. A pre-existing
-// config.toml (lectio's former format) at the default location is converted to
-// config.ini once, on first run, and left on disk. INI that fails to parse
-// falls back to defaults with a warning on stderr.
+// XDG_CONFIG_HOME via os.UserConfigDir()) -> built-in defaults. INI that fails
+// to parse falls back to defaults with a warning on stderr.
 package config
 
 import (
@@ -16,8 +14,6 @@ import (
 	"strconv"
 	"strings"
 
-	"github.com/pelletier/go-toml/v2"
-
 	"github.com/lukaszkasprzak/lectio/internal/bible"
 	"github.com/lukaszkasprzak/lectio/internal/calendar"
 	"github.com/lukaszkasprzak/lectio/internal/ini"
@@ -159,36 +155,36 @@ func NormalizeSiglaStyle(s string) string {
 	}
 }
 
-// Config holds lectio's user-configurable settings. The toml tags are used only
-// by the one-shot config.toml -> config.ini migration; the live format is INI.
+// Config holds lectio's user-configurable settings. The live format is INI,
+// parsed field-by-field in readINI and written by renderConfigINI.
 type Config struct {
-	SchemaVersion  int                        `toml:"schema_version"`
-	Lectionary     string                     `toml:"lectionary"`
-	Versions       []string                   `toml:"versions"`
-	DefaultVersion string                     `toml:"default_version"`
-	Width          int                        `toml:"width"`
-	All            bool                       `toml:"all"`
-	Offline        bool                       `toml:"offline"`
-	UILanguage     string                     `toml:"ui_language"`
-	ReadingLang    string                     `toml:"reading_lang"`
-	ReadingVersion string                     `toml:"reading_version"`
-	SiglaStyle     string                     `toml:"sigla_style"`
-	WebTheme       string                     `toml:"web_theme"`
-	WebPort        int                        `toml:"web_port"`
-	WebDisplay     string                     `toml:"web_display"`
-	WebMono        bool                       `toml:"web_mono"`
-	WebVersions    []string                   `toml:"web_versions"`
-	Pager          string                     `toml:"pager"`
-	Parts          map[string]map[string]bool `toml:"parts"`
+	SchemaVersion  int
+	Lectionary     string
+	Versions       []string
+	DefaultVersion string
+	Width          int
+	All            bool
+	Offline        bool
+	UILanguage     string
+	ReadingLang    string
+	ReadingVersion string
+	SiglaStyle     string
+	WebTheme       string
+	WebPort        int
+	WebDisplay     string
+	WebMono        bool
+	WebVersions    []string
+	Pager          string
+	Parts          map[string]map[string]bool
 
 	// Computed-calendar placement options (INI [calendar] section; INI-only).
-	CalEpiphany      string `toml:"-"`
-	CalAscension     string `toml:"-"`
-	CalCorpusChristi string `toml:"-"`
+	CalEpiphany      string
+	CalAscension     string
+	CalCorpusChristi string
 
 	// Use is the ordered stack of user calendar-layer ids (INI "use"); each id
 	// names a <CalendarsDir>/<id>.ini file layered over the universal calendar.
-	Use []string `toml:"-"`
+	Use []string
 }
 
 // PartShown reports whether a part renders: true unless explicitly set false.
@@ -403,8 +399,7 @@ func BooksPath() (string, error) {
 
 // UserBooksINI returns the bytes of the optional user books.ini (see BooksPath),
 // or nil when absent/unreadable -- callers then fall back to bible's embedded
-// default table. A former books.toml at the same location is converted to
-// books.ini once, on first read (the old file is kept).
+// default table.
 func UserBooksINI() []byte {
 	p, err := BooksPath()
 	if err != nil {
@@ -413,59 +408,7 @@ func UserBooksINI() []byte {
 	if b, err := os.ReadFile(p); err == nil {
 		return b
 	}
-	tomlPath := filepath.Join(filepath.Dir(p), "books.toml")
-	data, err := os.ReadFile(tomlPath)
-	if err != nil {
-		return nil
-	}
-	out := booksTOMLtoINI(data)
-	if out == nil {
-		return nil
-	}
-	_ = os.WriteFile(p, out, 0o644)
-	fmt.Fprintf(os.Stderr, "lectio: migrated %s -> books.ini (old file kept)\n", tomlPath)
-	return out
-}
-
-// booksTOMLtoINI converts a former books.toml (dialect -> book -> [forms]) into
-// books.ini. Returns nil if the TOML is unparseable.
-func booksTOMLtoINI(data []byte) []byte {
-	var raw map[string]map[string][]string
-	if err := toml.Unmarshal(data, &raw); err != nil {
-		return nil
-	}
-	var b strings.Builder
-	b.WriteString("# lectio book names & abbreviations, per dialect (migrated from books.toml).\n")
-	emit := func(d string) {
-		books := raw[d]
-		if books == nil {
-			return
-		}
-		fmt.Fprintf(&b, "\n[%s]\n", d)
-		keys := make([]string, 0, len(books))
-		for k := range books {
-			keys = append(keys, k)
-		}
-		sort.Strings(keys)
-		for _, k := range keys {
-			fmt.Fprintf(&b, "%s = %s\n", k, strings.Join(books[k], ", "))
-		}
-	}
-	seen := map[string]bool{"en": true, "pl": true, "la": true}
-	emit("en")
-	emit("pl")
-	emit("la")
-	others := make([]string, 0)
-	for d := range raw {
-		if !seen[d] {
-			others = append(others, d)
-		}
-	}
-	sort.Strings(others)
-	for _, d := range others {
-		emit(d)
-	}
-	return []byte(b.String())
+	return nil
 }
 
 // seedIfMissing writes the embedded default config to path if nothing is
@@ -482,24 +425,6 @@ func seedIfMissing(path string) error {
 	return os.WriteFile(path, renderConfigINI(Default()), 0o644)
 }
 
-// migrateFromTOML converts a former config.toml sitting next to iniPath into
-// config.ini, once. The old file is left in place (so the change is
-// reversible). A missing or unreadable config.toml is not an error.
-func migrateFromTOML(iniPath string) {
-	tomlPath := filepath.Join(filepath.Dir(iniPath), "config.toml")
-	data, err := os.ReadFile(tomlPath)
-	if err != nil {
-		return
-	}
-	cfg := Default()
-	if err := toml.Unmarshal(data, &cfg); err != nil {
-		return
-	}
-	normalize(&cfg)
-	_ = Save(cfg) // writes config.ini
-	fmt.Fprintf(os.Stderr, "lectio: migrated %s -> config.ini (old file kept)\n", tomlPath)
-}
-
 // Load reads lectio's configuration, following the package's resolution order
 // (see the package doc comment). It always returns a usable Config: on a
 // missing config dir or an INI parse error it falls back to Default() (warning
@@ -516,7 +441,6 @@ func Load() (Config, error) {
 
 	if isDefault {
 		if _, statErr := os.Stat(path); os.IsNotExist(statErr) {
-			migrateFromTOML(path) // convert a former config.toml if present
 			if err := seedIfMissing(path); err != nil {
 				return def, err
 			}
diff --git a/internal/config/config_test.go b/internal/config/config_test.go
index dd75808..4d172c0 100644
--- a/internal/config/config_test.go
+++ b/internal/config/config_test.go
@@ -68,8 +68,8 @@ func TestLoadOverride(t *testing.T) {
 	dir := t.TempDir()
 	t.Setenv("XDG_CONFIG_HOME", dir)
 	os.MkdirAll(filepath.Join(dir, "lectio"), 0o755)
-	os.WriteFile(filepath.Join(dir, "lectio", "config.toml"),
-		[]byte("offline = true\ndefault_version = \"wuj\"\n"), 0o644)
+	os.WriteFile(filepath.Join(dir, "lectio", "config.ini"),
+		[]byte("offline = true\ndefault_version = wuj\n"), 0o644)
 	cfg, _ := Load()
 	if !cfg.Offline || cfg.DefaultVersion != "wuj" {
 		t.Errorf("override not applied: %+v", cfg)
@@ -121,8 +121,8 @@ func TestWebDisplayLoadsSetting(t *testing.T) {
 	dir := t.TempDir()
 	t.Setenv("XDG_CONFIG_HOME", dir)
 	os.MkdirAll(filepath.Join(dir, "lectio"), 0o755)
-	os.WriteFile(filepath.Join(dir, "lectio", "config.toml"),
-		[]byte("web_display = \"vertical\"\n"), 0o644)
+	os.WriteFile(filepath.Join(dir, "lectio", "config.ini"),
+		[]byte("web_display = vertical\n"), 0o644)
 	cfg, err := Load()
 	if err != nil {
 		t.Fatal(err)
@@ -136,8 +136,8 @@ func TestWebDisplayNormalizesUnknown(t *testing.T) {
 	dir := t.TempDir()
 	t.Setenv("XDG_CONFIG_HOME", dir)
 	os.MkdirAll(filepath.Join(dir, "lectio"), 0o755)
-	os.WriteFile(filepath.Join(dir, "lectio", "config.toml"),
-		[]byte("web_display = \"bogus\"\n"), 0o644)
+	os.WriteFile(filepath.Join(dir, "lectio", "config.ini"),
+		[]byte("web_display = bogus\n"), 0o644)
 	cfg, err := Load()
 	if err != nil {
 		t.Fatal(err)
@@ -158,8 +158,8 @@ func TestUILanguageLoadsPL(t *testing.T) {
 	dir := t.TempDir()
 	t.Setenv("XDG_CONFIG_HOME", dir)
 	os.MkdirAll(filepath.Join(dir, "lectio"), 0o755)
-	os.WriteFile(filepath.Join(dir, "lectio", "config.toml"),
-		[]byte("ui_language = \"pl\"\n"), 0o644)
+	os.WriteFile(filepath.Join(dir, "lectio", "config.ini"),
+		[]byte("ui_language = pl\n"), 0o644)
 	cfg, err := Load()
 	if err != nil {
 		t.Fatal(err)
@@ -176,8 +176,8 @@ func TestUILanguagePreservesAnyCode(t *testing.T) {
 	dir := t.TempDir()
 	t.Setenv("XDG_CONFIG_HOME", dir)
 	os.MkdirAll(filepath.Join(dir, "lectio"), 0o755)
-	os.WriteFile(filepath.Join(dir, "lectio", "config.toml"),
-		[]byte("ui_language = \"FR\"\n"), 0o644)
+	os.WriteFile(filepath.Join(dir, "lectio", "config.ini"),
+		[]byte("ui_language = FR\n"), 0o644)
 	cfg, err := Load()
 	if err != nil {
 		t.Fatal(err)
@@ -210,8 +210,8 @@ func TestPagerLoadsSetting(t *testing.T) {
 	dir := t.TempDir()
 	t.Setenv("XDG_CONFIG_HOME", dir)
 	os.MkdirAll(filepath.Join(dir, "lectio"), 0o755)
-	os.WriteFile(filepath.Join(dir, "lectio", "config.toml"),
-		[]byte("pager = \"less -R\"\n"), 0o644)
+	os.WriteFile(filepath.Join(dir, "lectio", "config.ini"),
+		[]byte("pager = less -R\n"), 0o644)
 	cfg, err := Load()
 	if err != nil {
 		t.Fatal(err)
@@ -303,28 +303,6 @@ func TestUseLayers(t *testing.T) {
 	}
 }
 
-func TestMigrateTOMLToINI(t *testing.T) {
-	dir := t.TempDir()
-	t.Setenv("XDG_CONFIG_HOME", dir)
-	os.MkdirAll(filepath.Join(dir, "lectio"), 0o755)
-	// only the old TOML exists -> Load converts once and writes config.ini.
-	os.WriteFile(filepath.Join(dir, "lectio", "config.toml"),
-		[]byte("ui_language = \"pl\"\ndefault_version = \"wuj\"\n"), 0o644)
-	cfg, err := Load()
-	if err != nil {
-		t.Fatal(err)
-	}
-	if cfg.UILanguage != "pl" || cfg.DefaultVersion != "wuj" {
-		t.Errorf("migrated values wrong: %+v", cfg)
-	}
-	if _, err := os.Stat(filepath.Join(dir, "lectio", "config.ini")); err != nil {
-		t.Error("config.ini not written on migration")
-	}
-	if _, err := os.Stat(filepath.Join(dir, "lectio", "config.toml")); err != nil {
-		t.Error("old config.toml should be kept (reversible)")
-	}
-}
-
 func TestPartShown(t *testing.T) {
 	var empty Config
 	if !empty.PartShown("new", "psalm") {