Add delete_channel and keep_one_channel to the language table (after mute) and
fill all 20 language files (13 translated, English fallback for the rest), with
correct single-byte ISO-8859 accents. Wire them into the Delete Channel label,
confirmation and last-channel guard. The new strings land on empty voice-table
slots, so they play as silence (no crash, no .vpr regeneration).
flash.sh now always rebuilds the .gla language packs so edits to the language
files are actually picked up (previously a stale pack was re-flashed).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>