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, 6 insertions, 12 deletions

diff --git a/internal/calfeed/build.go b/internal/calfeed/build.go
index 216daff..8b4f7f0 100644
--- a/internal/calfeed/build.go
+++ b/internal/calfeed/build.go
@@ -4,6 +4,7 @@ import (
 	"time"
 
 	"github.com/lukaszkasprzak/lectio/internal/calendar"
+	"github.com/lukaszkasprzak/lectio/internal/naming"
 )
 
 // Build computes the day list from..to inclusive (calendar.Compute per date)
@@ -49,19 +50,12 @@ func celView(uiLang string, c calendar.Celebration) CelView {
 	}
 }
 
-// celebrationName resolves c's name in uiLang, falling back to English, then
-// a humanized slug (with the "ef-" prefix stripped and dashes turned to
-// spaces), then "(feria)" for an unnamed temporal day. Mirrors
-// cli.celebrationName.
+// celebrationName resolves c's name in uiLang via naming.CelebrationName
+// (name.<lang> -> English -> Latin -> humanized slug), then "(feria)" for an
+// unnamed temporal day.
 func celebrationName(uiLang string, c calendar.Celebration) string {
-	if n := c.Name[uiLang]; n != "" {
+	if n := naming.CelebrationName(uiLang, c); n != "" {
 		return n
 	}
-	if n := c.Name["en"]; n != "" {
-		return n
-	}
-	if c.Slug == "" {
-		return "(feria)"
-	}
-	return calendar.HumanizeSlug(c.Slug)
+	return "(feria)"
 }