Introduce an in-memory LRU cache for TTS audio with configurable
size and TTL via TTS_CACHE_MAX_SIZE_BYTES and TTS_CACHE_TTL_MS.
Return X-Cache headers (HIT/MISS) and set route runtime to nodejs.
Cache key includes provider, model, voice, speed, format, text,
and optional instructions.
Normalize non-Kokoro multi-voice input to the first token while
preserving full voice string in the cache key. Default Deepinfra
model to hexgrad/Kokoro-82M when none is provided.
Fix Deepinfra Kokoro behavior by enforcing single-voice selection:
- ui: only enable multi-select when provider supports >1 voices
- voice utils: Deepinfra max voices set to 1
- tests: gate provider selection and multi-voice tests by CI and
increase timeout for stability
70723f4c1d