feat(omnivoice): streaming /tts + language-safe sanitizer

Add a live-consumer streaming path and text sanitation to the OmniVoice
wrapper, so it can front speech-to-speech chat engines (not just the
asset-engine's batch WAV use).

- POST /tts: chunked 24 kHz mono s16le PCM (or open-ended WAV), driven by
  the adaptive buffer-ratchet scheduler. Emits the first sentence
  immediately, then ratchets chunk size up on OmniVoice's ~40x realtime
  headroom -> sub-second time-to-first-audio. Wire-compatible with
  chatterbox-fast /tts (both 24 kHz mono PCM). Batch /v1/audio/speech is
  unchanged for asset/file callers.

- scheduler.py: VENDORED byte-faithful copy of chatterbox-fast's pure-
  Python (torch-free) scheduler, pinned to commit 7631462 (v0.1.0/v0.1.1).
  Vendor-copy over a shared package (operator call 2026-06-19): the module
  has no GPU deps, so reuse it without dragging chatterbox-fast's torch
  tree into this image. Promote to a shared package only on a 3rd consumer
  or real drift.

- sanitize.py: language-safe TTS sanitizer run on both endpoints. Strips
  markdown, <think> blocks, HTML, and model control tokens; deliberately
  SKIPS the fork's English-only number/phone normalization that would
  corrupt OmniVoice's 600-language input. Preserves [laughter]-style tags.

- Refactor: shared GenParams base for SpeechRequest + TTSStreamRequest;
  single GEN_LOCK serializes generation (single-stream interactive).

- Dockerfile/playbook: copy + upload the two new modules; build-time
  `import app` smoke; correct stale "Gradio demo / no FastAPI" comments.

stacks/omnivoice/Dockerfile

@@ -4,8 +4,9 @@
 # languages) voice-cloning + voice-design TTS, diffusion-LM architecture,
 # Apache-2.0. Upstream ships a pip package + its own Gradio demo
 # (`omnivoice-demo`); there's no official image, so we build a thin CUDA
-# container around the pip package and run its Gradio server directly.
-# Unlike index-tts we DON'T need a FastAPI wrapper — OmniVoice serves itself.
+# container around the pip package and run our OWN FastAPI wrapper (app.py):
+# a batch OpenAI-style /v1/audio/speech plus a streaming /tts driven by the
+# vendored buffer-ratchet scheduler (scheduler.py) for live chat consumers.
 
 ARG CUDA_BASE=nvidia/cuda:12.8.0-cudnn-runtime-ubuntu22.04
 FROM ${CUDA_BASE}
@@ -41,9 +42,15 @@ RUN python -c "import omnivoice, fastapi, soundfile, uvicorn; print('omnivoice w
 
 WORKDIR /app
 COPY app.py /app/app.py
+COPY scheduler.py /app/scheduler.py
+COPY sanitize.py /app/sanitize.py
 COPY entrypoint.sh /usr/local/bin/entrypoint.sh
 RUN chmod +x /usr/local/bin/entrypoint.sh
 
+# Fail the build if the wrapper (incl. the vendored scheduler + sanitizer) won't
+# import. Model load is lazy (startup event), so this is a cheap CPU-only check.
+RUN python -c "import app; print('omnivoice app import OK')"
+
 EXPOSE 8001
 
 # Our wrapper exposes /healthz (200 once model + >=1 voice are loaded). Generous