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, 1 insertions, 1 deletions

diff --git a/internal/tui/reader.go b/internal/tui/reader.go
index 7f23f66..dc9141a 100644
--- a/internal/tui/reader.go
+++ b/internal/tui/reader.go
@@ -138,7 +138,7 @@ func (m ReaderModel) bookIndex(canonical string) int {
 func corpusVersions(cfg config.Config) []string {
 	var out []string
 	for _, v := range cfg.Versions {
-		if config.ValidVersion(v) && v != "bt" {
+		if config.ValidVersion(v) {
 			out = append(out, v)
 		}
 	}