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, 3 insertions, 0 deletions

diff --git a/internal/cli/cli.go b/internal/cli/cli.go
index 1fc7ac0..16ba753 100644
--- a/internal/cli/cli.go
+++ b/internal/cli/cli.go
@@ -207,6 +207,9 @@ func Run(args []string, stdin io.Reader, stdout, stderr io.Writer) int {
 	if dir, err := config.NamesDir(); err == nil {
 		naming.SetUserDir(dir)
 	}
+	if dir, err := config.UIDir(); err == nil {
+		i18n.SetUserDir(dir)
+	}
 	if lectionary != "" {
 		cfg.Lectionary = lectionary
 	}