feat(reminder): Use system TTS to announce schedule details when the reminder rings

[gac0812]

改动内容

响铃语音从"打包音频循环播放"改为系统 TextToSpeech 合成播报日程内容，按闹钟声道（STREAM_ALARM）循环播报，可被媒体音量独立控制。

播报文案

• 新增 ReminderSpeechFormatter（安卓）与 reminderSpeech.ts（JS），生成如「晨会，时间到了。现在已经9点0分了。」的文案
• 整点播"X点"，非整点播"X点X分"；日程跨天时带"X月X日"
• 标题超长（>80 字）截断，空标题回退"未命名日程"

数据链路

• speech_text 贯穿全链路：JS 端 LocalReminderApplication 计算 → NativeAlarmScheduler/TimeflowAlarmBridge → 安卓 AlarmModule → AlarmScheduler 持久化 → 触发时 AlarmSoundService 取出并 TTS 播报
• 兼容旧数据：已持久化的旧闹钟无 speech_text 时，由 ExtractedExtras.from 按当前时间回退生成

安卓侧

• TextToSpeech 优先简体中文语音，缺失回退系统默认语言
• 音频属性 USAGE_ALARM，播报完成后 1.5s 循环

测试

• 新增 ReminderSpeechFormatterTest（安卓单测）覆盖整点/非整点/跨天/超长标题/空标题
• 新增 ReminderSpeechFormatterTest 对应的 JS 文案格式测试
• 更新 nativeAlarmScheduler.test.ts 适配 native.schedule 新增的第 4 个 speechText 参数，并新增一条断言 speech_text 被正确转发

本地验证

• ./gradlew :timeflow-alarm:testDebugUnitTest ✅
• npm run check（lint + format + typecheck + 64 套件 597 测试）✅
• npx expo export --platform android ✅

Closes #350

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!

[fennoai]

Review

The JS-to-native scheduling and persistence additions are wired consistently, and the formatter coverage is focused. One Android intent handoff still drops the new speech payload, so the advertised schedule-specific TTS text is not used on the normal firing path (and on snooze retries). The fixed-range diff is clean under git diff --check; the advertised Gradle test could not be run because this checkout has no Gradle wrapper, and the JS test command is blocked by a non-executable local vitest binary.

[gac0812]

Codecov follow-up: commit 1079e8d adds reminderSpeech.test.ts covering missing schedule time, invalid timestamps, invalid timezones, all-day/timed formatting, and title normalization. Local Jest coverage reports 24/24 lines covered for src/features/reminder/domain/reminderSpeech.ts. The targeted formatter suite passes (6 tests); the full local Jest run passes 64 suites / 591 tests when excluding the pre-existing ScheduleCalendarScreen.test.tsx assertion affected by unrelated working-tree changes.