## Summary
- Add `minimax-speech` TTS provider using MiniMax's T2A v2 API
- Implement streaming SSE response with hex-encoded audio decoding (no
external dependency required)
- Include a curated static voice list (English and Mandarin voices)
- Add `speech-2.8-hd` (default) and `speech-2.8-turbo` model entries
- Support configurable base URL defaulting to `https://api.minimax.io`
- Add i18n translations for all 9 supported locales
Closes#1274
## Implementation Details
The provider uses a custom `fetch` interceptor within the
`SpeechProvider` interface to:
1. Parse the incoming OpenAI-style request (`input`, `voice`, `model`)
2. Call MiniMax's `/v1/t2a_v2` SSE streaming endpoint
3. Decode hex-encoded audio chunks from SSE events (skipping the summary
chunk with `status=2`)
4. Return a concatenated `audio/mpeg` response
## API Reference
- TTS: https://platform.minimax.io/docs/api-reference/speech-t2a-http