v1.2.1 - Contraction Fix

FIXED: English contractions (don't, can't, won't) now work after language toggle
- Swipe typing: "dont" → "don't" works after toggling French → English
- Touch typing: Contraction suggestions work after any language switch

Root cause: Contraction keys weren't added to beam search trie when switching back to English. Now properly inserts contraction keys into vocabulary trie on language change.
