Update v1.3 — All languages bundled, garbled text fixed

- FIX: Garbled block characters (▁/□) that could appear in Chinese and other
translations are cleaned up. Reported by a Simplified Chinese review — thanks!
- NEW: ALL translation languages are now bundled. Chinese, Korean, Spanish,
French, German, Portuguese, Italian and Russian no longer need a first-use
download — everything works fully offline, out of the box. This also fixes
"translation never works" on network-restricted connections, where the
first-use model download could silently fail.
- Under the hood: our release checks now machine-test every supported language
end-to-end through the real UI before every update ships.

Note: this update is larger than usual (~900MB) because of the bundled models.