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, 10 insertions, 11 deletions

diff --git a/internal/liturgy/section.go b/internal/liturgy/section.go
index 1e446a1..dcca7b5 100644
--- a/internal/liturgy/section.go
+++ b/internal/liturgy/section.go
@@ -17,19 +17,18 @@ type Section struct {
 	Paragraphs                               [][]string
 }
 
-// DayInfo is the day's liturgical identity, source-language (Polish for the
-// modern niedziela.pl lectionary, English/Latin for the traditional
-// missalemeum) -- never translated, like Section's own Heading/Citation.
-// A source that carries no such data (or an unrecognised page/response
-// shape) yields a zero DayInfo; callers must treat that as "omit the
-// header", never as an error.
+// DayInfo is the day's liturgical identity from the offline calendar engine.
+// Name follows the UI language where the calendar data has a localized name
+// (else English); Colour is normalized. A day that carries no celebration name
+// yields a zero DayInfo; callers must treat that as "omit the header", never as
+// an error.
 type DayInfo struct {
-	// Name is the celebration, e.g. "Święto św. Marii Magdaleny" (modern) or
-	// "St. Mary Magdalene" (traditional).
+	// Name is the celebration, e.g. "św. Marii Magdaleny" (pl UI, where the
+	// calendar data has a Polish name) or "Saint Mary Magdalene" (en).
 	Name string
-	// Season is the temporal context, e.g. "Feria IV after VIII Sunday
-	// after Pentecost" (traditional); always "" for the modern lectionary,
-	// whose temporal is folded into Name on temporal days.
+	// Season is the temporal context; currently left empty by the offline
+	// loader, since the celebration name already carries the temporal identity
+	// on temporal days.
 	Season string
 	// Colour is the normalized liturgical colour: "white", "green",
 	// "violet", "red", "rose", or "" when unknown/unmapped.