Add SpeechConfig with typed configuration and startup validation for
STT (Whisper/Speaches), TTS default (Kokoro), TTS premium (Chatterbox),
and TTS fallback (Piper/OpenedAI). Includes registerAs factory for
NestJS ConfigModule integration, .env.example documentation, and 51
unit tests covering all validation paths.
Refs #401
Adds directory-specific agent context templates for AI-assisted
development across all apps and packages.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
