naming: localise liturgical day names in any language

Add internal/naming, which renders temporal day names and celebration
display names from the calendar engine's slugs in any language. English is
the built-in baseline; a language is data -- an embedded lang/<code>.ini
(pl shipped) and/or a user file at <config dir>/names/<code>.ini that
overrides it key by key. Names compose from a small vocabulary plus
per-language format templates, so word order and grammatical case can
differ (e.g. Polish genitive "3. Niedziela Okresu Zwykłego"); any string a
language omits falls back to English.

- Move day-name generation out of calendar (calendar.HumanizeSlug removed,
  calendar stays a pure engine) into naming.DayName; the English golden
  cases carry over verbatim.
- naming.CelebrationName unifies the three duplicated resolvers
  (cli/readings/calfeed): name.<lang> -> English -> Latin -> humanized slug.
  Saint names stay in the calendar data (name.<lang>), overridable via
  calendar layers.
- config: ui_language now accepts any code (lower-cased, not clamped to
  en/pl) so names/<code>.ini applies; UI chrome still resolves en/pl and
  falls back to English. Add NamesDir(); wire naming.SetUserDir (and the
  previously unwired bible.SetUserCorporaDir) in the TUI and web mains too,
  so external corpora and name files work across all three binaries.

1 files changed, 7 insertions, 4 deletions

diff --git a/internal/config/config_test.go b/internal/config/config_test.go
index 1035426..dd75808 100644
--- a/internal/config/config_test.go
+++ b/internal/config/config_test.go
@@ -169,18 +169,21 @@ func TestUILanguageLoadsPL(t *testing.T) {
 	}
 }
 
-func TestUILanguageNormalizesUnknown(t *testing.T) {
+func TestUILanguagePreservesAnyCode(t *testing.T) {
+	// Any ui_language code is kept (lower-cased): it drives day/saint-name
+	// localisation via names/<code>.ini. The UI chrome, resolved through
+	// i18n.Get, still falls back to English for a code it has no table for.
 	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 = \"bogus\"\n"), 0o644)
+		[]byte("ui_language = \"FR\"\n"), 0o644)
 	cfg, err := Load()
 	if err != nil {
 		t.Fatal(err)
 	}
-	if cfg.UILanguage != "en" {
-		t.Errorf("UILanguage = %q, want %q (normalized from bogus)", cfg.UILanguage, "en")
+	if cfg.UILanguage != "fr" {
+		t.Errorf("UILanguage = %q, want %q (lower-cased, not clamped)", cfg.UILanguage, "fr")
 	}
 }