Key sound and haptic styles; nine-key lone key shows its initial

[Slacker-LLC]

Summary

Folds into a re-release of 0.0.5-beta.1 (the published beta5 will be replaced).

• Key sounds: 按键音效 offers 系统 plus five clicks synthesized by scripts/generate_key_sounds.py (清脆, 机械, 木质, 打字机, 气泡; 48 kHz mono, under 80 ms, deterministic, no third-party rights). Played through SoundPool as UI sonification; choosing one previews it once.
• Haptic feel: 震动手感 offers 清脆 (default: PRIMITIVE_TICK / EFFECT_TICK / 8 ms), 有力 (PRIMITIVE_CLICK / EFFECT_CLICK / 12 ms) and 系统 (KEYBOARD_TAP). One-shot fallbacks stay at 8–12 ms because longer pulses ring on linear motors (e.g. Xiaomi's X-axis motor), the "muddy" feel reported on a Xiaomi 15. The strength slider scales both bundled styles.
• Diagnostics: 关于 → 诊断 lists the vibrator's primitive and amplitude support.
• Nine-key: a lone 4 / 5 / 7 / 8 / 9 now shows the top candidate's initial (4 → h) instead of the bare digit; the rail highlights the same letter.
• Both styles are in the user-data archive; the enums live in data so panel and keyboard can share them.

Test plan

• testDebugUnitTest 375/375 (new aLoneKeyAlignsToTheTopCandidatesInitial), lintDebug no errors
• Emulator API 36: preferences show 音效 and 震动手感 rows; selecting 机械 saves key_sound_style=mechanical and an app-owned sonification track plays; 清脆 haptics log Primitive=TICK(scale=…); nine-key 4/5/7/8 show h/l/s/t with the rail matching
• Real-device haptic feel (Xiaomi 15)

🤖 Generated with Claude Code