i18n: make all UI chrome user-translatable via ui/<code>.ini

The interface chrome (version labels, TUI keybar/messages, CLI banner words,
web control labels, section-heading words) was English/Polish hardcoded in Go.
It is now data: the English and Polish tables ship as embedded lang/en.ini and
lang/pl.ini, and any language is user-overridable at <config>/ui/<code>.ini,
resolved per key with an English fallback. With ui_language = <code> plus a
names/<code>.ini, the WHOLE interface -- chrome, day names, saint names -- is
translatable without a rebuild.

- i18n.Get loads the embedded English baseline, overlays the embedded/user
  language file, caches per lang; field <-> INI-key mapping is by reflection
  (lang.go) so the tables and files stay in sync automatically. Edge-space
  values (e.g. "error: ") are double-quoted so the INI trim keeps them. The
  Go tables move to golden_test.go; TestGoldenMatchesEmbedded asserts the
  embedded files still parse back to them, and TestGenerateLangFiles
  regenerates them (LECTIO_GEN=1).
- config.UIDir(); wire i18n.SetUserDir in the CLI, TUI and web entry points.
- README/config: document ui/<code>.ini alongside names/<code>.ini.

1 files changed, 191 insertions, 0 deletions

diff --git a/internal/i18n/golden_test.go b/internal/i18n/golden_test.go
new file mode 100644
index 0000000..e6dc00a
--- /dev/null
+++ b/internal/i18n/golden_test.go
@@ -0,0 +1,191 @@
+package i18n
+
+import (
+	"reflect"
+	"testing"
+)
+
+// enUI and plUI are the golden chrome tables. They are the SOURCE the embedded
+// lang/en.ini and lang/pl.ini are generated from (TestGenerateLangFiles), and
+// TestGoldenMatchesEmbedded asserts the embedded files still parse back to them
+// -- so a hand-edit to a lang file that drifts from these is caught.
+var enUI = UI{
+	Version: map[string]string{
+		"wuj": "Wujek (Polish)",
+		"vul": "Vulgate (Latin)",
+		"grb": "Greek",
+		"drb": "Douay-Rheims (English)",
+	},
+	PartLabel: map[string]string{
+		"pierwsze_czytanie": "1st reading",
+		"psalm":             "Psalm",
+		"drugie_czytanie":   "2nd reading",
+		"aklamacja":         "Acclamation",
+		"ewangelia":         "Gospel",
+	},
+	FooterKeys:            "tab/⇧tab version  ←/→ day  d date  j/k scroll  space/b page  g/G top/bottom  q quit",
+	Loading:               "loading…",
+	NoReadingsFor:         "no readings for ",
+	ErrorPrefix:           "error: ",
+	ErrorHint:             "change date (←/→)",
+	JumpPrompt:            "go to date (YYYY-MM-DD)",
+	ReaderTitle:           "reader — pick a book",
+	ReaderPickKeys:        "type to filter  ↑/↓ move  enter open  esc quit",
+	ReaderReadKeys:        "n/p chapter  c go-to  tab version  j/k scroll  m mark  b bookmarks  esc books  q quit",
+	ReaderNoText:          "(no text in this version)",
+	ReaderNoMatch:         "(no matching books)",
+	ReaderMarkPrompt:      "note (enter to save, esc to cancel)",
+	ReaderBookmarksTitle:  "bookmarks",
+	ReaderBookmarksKeys:   "j/k move  enter open  d delete  esc back  q quit",
+	ReaderNoBookmarks:     "no bookmarks yet — press m while reading",
+	ReaderMarkVerseKeys:   "↑/↓ pick verse  enter add note  esc cancel",
+	ReaderConfirmDelete:   "Delete this bookmark?",
+	ReaderConfirmKeys:     "y = delete    n = cancel",
+	ReaderMarkNote:        "note",
+	ReaderMarkTags:        "tags",
+	ReaderMarkHelp:        "enter save · tab switch field · esc cancel",
+	ReaderJumpChapter:     "go to chapter",
+	ReaderJumpChapterKeys: "enter go · esc cancel",
+	BannerGospel:          "Gospel",
+	BannerReadings:        "Readings",
+	BannerConnective:      "for",
+	Months:                [12]string{"January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"},
+	Lectionary:            "lectionary",
+	OptModern:             "modern",
+	OptTraditional:        "traditional",
+	Parts:                 "parts",
+	OptGospel:             "Gospel",
+	OptAll:                "all parts",
+	Layout:                "layout",
+	OptHorizontal:         "horizontal",
+	OptColumns:            "columns",
+	OptInterlinear:        "interlinear",
+	Theme:                 "theme",
+	Mono:                  "mono",
+	NoInterlinearVerses:   "(no verses to align)",
+	NavReader:             "reader",
+	WebBook:               "book",
+	WebChapter:            "chapter",
+	NavHome:               "home",
+	NavSettings:           "settings",
+	NavBookmarks:          "bookmarks",
+	WebVerseOptional:      "verse (optional)",
+	WebTagsPlaceholder:    "tags, comma-separated",
+	WebAddBookmark:        "bookmark",
+	WebAllTags:            "all",
+	WebNoBookmarks:        "No bookmarks yet.",
+	WebDelete:             "delete",
+	WebSaved:              "Saved.",
+	WebUILang:             "UI language",
+	WebSiglaStyle:         "sigla style",
+	WebDefaultVersion:     "default version",
+	WebVersions:           "versions",
+	WebWebVersions:        "web versions",
+	WebOffline:            "offline",
+	WebWidth:              "width",
+	WebPort:               "web port",
+	WebPager:              "pager",
+	WebSave:               "Save",
+	Export:                "download",
+	Calendar:              "month calendar",
+	NoReadingsDay:         "no readings for this day",
+	NoVersion:             "(not in %s)",
+	NoVersionPartial:      "(not in %s: %s)",
+	NoReference:           "(no reference)",
+	NoReferenceErr:        "(no reference: %v)",
+}
+
+var plUI = UI{
+	Version: map[string]string{
+		"wuj": "Wujek (pol.)",
+		"vul": "Wulgata (lac.)",
+		"grb": "Grecki",
+		"drb": "Douay-Rheims (ang.)",
+	},
+	PartLabel: map[string]string{
+		"pierwsze_czytanie": "1. czytanie",
+		"psalm":             "Psalm",
+		"drugie_czytanie":   "2. czytanie",
+		"aklamacja":         "Aklamacja",
+		"ewangelia":         "Ewangelia",
+	},
+	FooterKeys:            "tab/⇧tab wersja  ←/→ dzień  d data  j/k przewiń  spacja/b strona  g/G góra/dół  q wyjście",
+	Loading:               "ładowanie…",
+	NoReadingsFor:         "brak czytań na ",
+	ErrorPrefix:           "błąd: ",
+	ErrorHint:             "zmień datę (←/→)",
+	JumpPrompt:            "przejdź do daty (RRRR-MM-DD)",
+	ReaderTitle:           "czytnik — wybierz księgę",
+	ReaderPickKeys:        "wpisz, by filtrować  ↑/↓ ruch  enter otwórz  esc wyjście",
+	ReaderReadKeys:        "n/p rozdział  c skok  tab wersja  j/k przewiń  m zakładka  b zakładki  esc księgi  q wyjście",
+	ReaderNoText:          "(brak tekstu w tej wersji)",
+	ReaderNoMatch:         "(brak pasujących ksiąg)",
+	ReaderMarkPrompt:      "notatka (enter zapisz, esc anuluj)",
+	ReaderBookmarksTitle:  "zakładki",
+	ReaderBookmarksKeys:   "j/k ruch  enter otwórz  d usuń  esc wróć  q wyjście",
+	ReaderNoBookmarks:     "brak zakładek — naciśnij m podczas czytania",
+	ReaderMarkVerseKeys:   "↑/↓ wybierz werset  enter notatka  esc anuluj",
+	ReaderConfirmDelete:   "Usunąć zakładkę?",
+	ReaderConfirmKeys:     "y = usuń    n = anuluj",
+	ReaderMarkNote:        "notatka",
+	ReaderMarkTags:        "tagi",
+	ReaderMarkHelp:        "enter zapisz · tab pole · esc anuluj",
+	ReaderJumpChapter:     "przejdź do rozdziału",
+	ReaderJumpChapterKeys: "enter przejdź · esc anuluj",
+	BannerGospel:          "Ewangelia",
+	BannerReadings:        "Czytania",
+	BannerConnective:      "na",
+	Months:                [12]string{"Styczeń", "Luty", "Marzec", "Kwiecień", "Maj", "Czerwiec", "Lipiec", "Sierpień", "Wrzesień", "Październik", "Listopad", "Grudzień"},
+	Lectionary:            "lekcjonarz",
+	OptModern:             "nowy",
+	OptTraditional:        "tradycyjny",
+	Parts:                 "zakres",
+	OptGospel:             "Ewangelia",
+	OptAll:                "wszystkie części",
+	Layout:                "układ",
+	OptHorizontal:         "poziomo",
+	OptColumns:            "kolumny",
+	OptInterlinear:        "interlinearnie",
+	Theme:                 "motyw",
+	Mono:                  "mono",
+	NoInterlinearVerses:   "(brak wersetów do zestawienia interlinearnego)",
+	NavReader:             "czytnik",
+	WebBook:               "księga",
+	WebChapter:            "rozdział",
+	NavHome:               "strona główna",
+	NavSettings:           "ustawienia",
+	NavBookmarks:          "zakładki",
+	WebVerseOptional:      "werset (opcjonalnie)",
+	WebTagsPlaceholder:    "tagi, oddzielone przecinkami",
+	WebAddBookmark:        "zakładka",
+	WebAllTags:            "wszystkie",
+	WebNoBookmarks:        "Brak zakładek.",
+	WebDelete:             "usuń",
+	WebSaved:              "Zapisano.",
+	WebUILang:             "język interfejsu",
+	WebSiglaStyle:         "styl sigli",
+	WebDefaultVersion:     "wersja domyślna",
+	WebVersions:           "wersje",
+	WebWebVersions:        "wersje web",
+	WebOffline:            "offline",
+	WebWidth:              "szerokość",
+	WebPort:               "port web",
+	WebPager:              "pager",
+	WebSave:               "Zapisz",
+	Export:                "pobierz",
+	Calendar:              "kalendarz miesiąca",
+	NoReadingsDay:         "brak czytań na ten dzień",
+	NoVersion:             "(brak w „%s”)",
+	NoVersionPartial:      "(brak w „%s”: %s)",
+	NoReference:           "(brak odwołania)",
+	NoReferenceErr:        "(brak odwołania: %w)",
+}
+
+func TestGoldenMatchesEmbedded(t *testing.T) {
+	if got := Get("en"); !reflect.DeepEqual(got, enUI) {
+		t.Errorf("Get(en) != golden enUI:\n got %+v\nwant %+v", got, enUI)
+	}
+	if got := Get("pl"); !reflect.DeepEqual(got, plUI) {
+		t.Errorf("Get(pl) != golden plUI:\n got %+v\nwant %+v", got, plUI)
+	}
+}