refactor: remove the niedziela/missalemeum scrapers, bt, traditional_lang

The daily view now computes entirely offline (previous commit), so retire the
network path and everything that served it:

- Delete internal/tradlit (missalemeum) and the niedziela scraper from
  internal/liturgy (fetch/store/parse + fixtures); keep Section, DayInfo and
  ExtractCitation.
- Remove the "bt" version everywhere (render gatherBT + branches, config,
  i18n, web form, TUI) and bible.ToEnglishRef (Polish citation converter).
  A legacy config carrying "bt" migrates to "wuj" on load (config.migrateBT).
- Remove the traditional_lang config field and the -g/--lang flag from all
  three binaries.
- Drop the now-dead flags -R/--refresh, -o/--offline, -u/--update,
  -C/--clean and the harvest/clean commands.
- New defaults: versions = wuj,vul,grb,drb; default_version = vul.

Update the README (offline-by-design, no harvest/update), help text, and
stale niedziela/bt doc comments. Tests updated for the offline reality;
go test ./... and go vet ./... are clean, all three binaries build and run
offline (OF + EF, compare, web).

1 files changed, 84 insertions, 53 deletions

diff --git a/internal/config/config.go b/internal/config/config.go
index a9e00d1..31e9078 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -32,9 +32,8 @@ const configHeader = `# lectio configuration (INI). Full-line comments only (# o
 #
 # Allowed values:
 #   lectionary        new | traditional        (new = modern OF; traditional = 1962 EF)
-#   traditional_lang  pl | en                  (vernacular for traditional propers)
-#   versions          any of: bt, wuj, vul, grb, drb   (comma list; bt = Biblia Tysiąclecia)
-#   default_version   bt | wuj | vul | grb | drb
+#   versions          any of: wuj, vul, grb, drb        (comma list)
+#   default_version   wuj | vul | grb | drb
 #   width             integer; 0 = detect terminal width
 #   all               true | false             (all readings, or just the gospel)
 #   offline           true | false             (never fetch; cache/sigla only)
@@ -46,7 +45,7 @@ const configHeader = `# lectio configuration (INI). Full-line comments only (# o
 #   web_port          integer; 0 = try 1099, then any free port
 #   web_display       horizontal | vertical | interlinear
 #   web_mono          true | false             (monospace reading face in the web UI)
-#   web_versions      any of: bt, wuj, vul, grb, drb (comma list); empty = just default_version
+#   web_versions      any of: wuj, vul, grb, drb (comma list); empty = just default_version
 #   pager             shell command, e.g. less -R; empty = off
 #   use               calendar layers to stack over the universal calendar: names of
 #                     ~/.config/lectio/calendars/<name>.ini files (comma list, order = precedence)
@@ -65,17 +64,18 @@ const configHeader = `# lectio configuration (INI). Full-line comments only (# o
 // -v/--version output (lectio, lectio-ui, lectio-web).
 const Version = "0.44.0"
 
-// validVersions are the five scripture versions lectio understands.
+// validVersions are the scripture versions lectio understands. All are
+// embedded corpora; the former "bt" (the niedziela.pl modern scrape) is gone
+// and a legacy config carrying it is migrated to "wuj" on load (see Load).
 var validVersions = map[string]bool{
-	"bt":  true,
 	"wuj": true,
 	"vul": true,
 	"grb": true,
 	"drb": true,
 }
 
-// ValidVersion reports whether v is one of the five scripture versions
-// lectio understands (bt, wuj, vul, grb, drb).
+// ValidVersion reports whether v is one of the scripture versions lectio
+// understands (wuj, vul, grb, drb).
 func ValidVersion(v string) bool {
 	return validVersions[v]
 }
@@ -150,25 +150,24 @@ 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.
 type Config struct {
-	SchemaVersion   int                        `toml:"schema_version"`
-	Lectionary      string                     `toml:"lectionary"`
-	TraditionalLang string                     `toml:"traditional_lang"`
-	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                        `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"`
 
 	// Computed-calendar placement options (INI [calendar] section; INI-only).
 	CalEpiphany      string `toml:"-"`
@@ -257,23 +256,22 @@ func (c Config) Selection() calendar.Selection {
 // is found and as the base that a partial config file overrides.
 func Default() Config {
 	return Config{
-		SchemaVersion:   1,
-		Lectionary:      "new",
-		TraditionalLang: "pl",
-		Versions:        []string{"bt", "wuj", "vul", "grb", "drb"},
-		DefaultVersion:  "bt",
-		Width:           0,
-		All:             false,
-		Offline:         false,
-		UILanguage:      "en",
-		SiglaStyle:      "auto",
-		WebTheme:        "transfiguration",
-		WebPort:         0,
-		WebDisplay:      "horizontal",
-		WebMono:         false,
-		WebVersions:     nil,
-		Pager:           "",
-		Parts:           nil,
+		SchemaVersion:  1,
+		Lectionary:     "new",
+		Versions:       []string{"wuj", "vul", "grb", "drb"},
+		DefaultVersion: "vul",
+		Width:          0,
+		All:            false,
+		Offline:        false,
+		UILanguage:     "en",
+		SiglaStyle:     "auto",
+		WebTheme:       "transfiguration",
+		WebPort:        0,
+		WebDisplay:     "horizontal",
+		WebMono:        false,
+		WebVersions:    nil,
+		Pager:          "",
+		Parts:          nil,
 	}
 }
 
@@ -471,6 +469,45 @@ func normalize(cfg *Config) {
 	cfg.WebDisplay = NormalizeDisplay(cfg.WebDisplay)
 	cfg.UILanguage = NormalizeUILanguage(cfg.UILanguage)
 	cfg.SiglaStyle = NormalizeSiglaStyle(cfg.SiglaStyle)
+	migrateBT(cfg)
+}
+
+// migrateBT rewrites a legacy "bt" version (the retired niedziela.pl scrape,
+// which had no embedded corpus) to "wuj" wherever a saved config still carries
+// it, so an existing config keeps loading after bt was removed. In a version
+// list "bt" becomes "wuj" only when "wuj" is not already present; otherwise it
+// is dropped, so no list gains a duplicate column.
+func migrateBT(cfg *Config) {
+	if cfg.DefaultVersion == "bt" {
+		cfg.DefaultVersion = "wuj"
+	}
+	cfg.Versions = migrateBTList(cfg.Versions)
+	cfg.WebVersions = migrateBTList(cfg.WebVersions)
+}
+
+func migrateBTList(versions []string) []string {
+	if len(versions) == 0 {
+		return versions
+	}
+	hasWuj := false
+	for _, v := range versions {
+		if v == "wuj" {
+			hasWuj = true
+			break
+		}
+	}
+	out := make([]string, 0, len(versions))
+	for _, v := range versions {
+		if v != "bt" {
+			out = append(out, v)
+			continue
+		}
+		if !hasWuj {
+			out = append(out, "wuj")
+			hasWuj = true
+		}
+	}
+	return out
 }
 
 // readINI parses INI bytes into a Config over Default(). Absent keys keep the
@@ -520,8 +557,6 @@ func applyScalar(cfg *Config, key, val string) {
 		cfg.SchemaVersion = atoiOr(val, cfg.SchemaVersion)
 	case "lectionary":
 		cfg.Lectionary = val
-	case "traditional_lang":
-		cfg.TraditionalLang = val
 	case "versions":
 		cfg.Versions = ini.List(val)
 	case "default_version":
@@ -569,20 +604,17 @@ func validate(cfg Config) error {
 	if cfg.Lectionary != "new" && cfg.Lectionary != "traditional" {
 		return fmt.Errorf("config: invalid lectionary %q (must be \"new\" or \"traditional\")", cfg.Lectionary)
 	}
-	if cfg.TraditionalLang != "pl" && cfg.TraditionalLang != "en" {
-		return fmt.Errorf("config: invalid traditional_lang %q (must be \"pl\" or \"en\")", cfg.TraditionalLang)
-	}
 	for _, v := range cfg.Versions {
 		if !validVersions[v] {
-			return fmt.Errorf("config: invalid version %q in versions (must be one of bt, wuj, vul, grb, drb)", v)
+			return fmt.Errorf("config: invalid version %q in versions (must be one of wuj, vul, grb, drb)", v)
 		}
 	}
 	if !validVersions[cfg.DefaultVersion] {
-		return fmt.Errorf("config: invalid default_version %q (must be one of bt, wuj, vul, grb, drb)", cfg.DefaultVersion)
+		return fmt.Errorf("config: invalid default_version %q (must be one of wuj, vul, grb, drb)", cfg.DefaultVersion)
 	}
 	for _, v := range cfg.WebVersions {
 		if !validVersions[v] {
-			return fmt.Errorf("config: invalid version %q in web_versions (must be one of bt, wuj, vul, grb, drb)", v)
+			return fmt.Errorf("config: invalid version %q in web_versions (must be one of wuj, vul, grb, drb)", v)
 		}
 	}
 	return nil
@@ -613,7 +645,6 @@ func renderConfigINI(cfg Config) []byte {
 	b.WriteString("\n")
 	fmt.Fprintf(&b, "schema_version = %d\n", cfg.SchemaVersion)
 	fmt.Fprintf(&b, "lectionary = %s\n", cfg.Lectionary)
-	fmt.Fprintf(&b, "traditional_lang = %s\n", cfg.TraditionalLang)
 	fmt.Fprintf(&b, "versions = %s\n", strings.Join(cfg.Versions, ", "))
 	fmt.Fprintf(&b, "default_version = %s\n", cfg.DefaultVersion)
 	fmt.Fprintf(&b, "width = %d\n", cfg.Width)