feat(voice): add realtime dictation modes

[Shujakuinkuraudo]

Summary

• add selectable voice modes in settings for assistant, local dictation, and ElevenLabs transcription
• add browser-local speech-to-text and ElevenLabs realtime transcription hooks for the composer
• add hub support for ElevenLabs realtime scribe tokens and transcription language normalization

Testing

• bun run typecheck:web
• bun run typecheck:hub
• bun run build:web
• bun run build:single-exe

Closes #462

[Shujakuinkuraudo]

Supplementary note: this change has been tested locally.

Validated with:

• bun run typecheck:web
• bun run typecheck:hub
• bun run build:web
• bun run build:single-exe

I also verified the updated binary path and exercised the voice-mode flow during development, including the new realtime dictation path.