fix: honor selected chat voice

[rogerchappel]

Summary

• Pass the resolved chat voice settings into chat message speaker actions.
• Send selected voice settings to /api/tts for manual message playback.
• Match browser fallback voices by selected voice id or name, including browser and macOS say selections.

Verification

• pnpm typecheck
• git diff --check
• pnpm lint:check (passes with existing warnings)
• pre-push hook: pnpm typecheck && pnpm build

Risk

Low to medium. User-facing TTS behavior changes, scoped to selected voice propagation and fallback voice selection.