- levels.test.ts: change length assertion to 16, add newKeys tests for levels 7-16
- levels.test.ts: add Level 16 allKeys completeness test (all QWERTZ keys)
- words.test.ts: extend all loops from 6 to 16 levels, add validateWordList test
- companion.test.ts: fix unknown-letter test to use '@' (z now has a fallback entry)
- Full QWERTZ keyboard with DE and CH layout support
- Finger color mapping for all keys per spec section 8.3
- renderKeyboard, highlightKey, pressKey, updateKeyboardForLevel exports
- CSS: pulse animation for target key, press animation on keydown
- Inactive keys grayed at 0.5 opacity, active keys with finger colors
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>