Define the abstract interface for the speech subsystem: SpeechBackend ABC
with transcribe/health/supported_formats methods, TranscriptionResult and
Segment dataclasses for structured transcription output.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Add SpeechConfig dataclass with backend, model, language, device, and
compute_type fields. Wire it into JarvisConfig and load_config() so
[speech] TOML sections are loaded automatically.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>