feat: Section Announce (TTS)

[ElBeh]

Description

Announce section names via text-to-speech when the active section changes
during playback. Helps guitarists keep their eyes on the fretboard instead
of looking at the screen for section transitions.

Estimated effort: ~2–3h

Requirements

• Use browser-native Web Speech API (SpeechSynthesis)
• Announce section type + label on section change during playback
• Toggle in PlayerControls (on/off, persisted in localStorage)
• Configurable speech rate (slightly faster than default, e.g. 1.2)
• Optional voice selector (OS-dependent available voices)
• No announcement when seeking manually (only during continuous playback)
• Works for both audio songs and dummy songs
• Band Sync: announcement is local per client (not synced)

Implementation

• New hook: src/hooks/useSectionAnnounce.ts
• Toggle button in PlayerControls.tsx

Decisions

• Web Speech API over external TTS libraries: zero bundle size, offline-capable
• Speech rate default 1.2 to keep announcements brief and non-intrusive
• Upgrade path: pre-render section names into AudioBuffers via OfflineAudioContext if latency becomes an issue