Multi-pass warmup and smaller chunk_size to fix HA timeout

torch.compile with dynamic=True still specializes per shape family on
first call. The warmup was running one text length, leaving real requests
to JIT-compile their own shapes (15-22s for first chunk). HA freezes
because it gets no AudioChunk for 22 seconds.

Fix:
- Run 3 warmup passes (short/medium/long text) so torch.compile builds
  a dynamic shape graph covering the range HA actually sends. Real
  requests then hit a cached compilation and synthesize in 3-8s.
- Reduce default chunk_size from 300 to 120 chars so the first text
  chunk is shorter, producing faster synthesis and earlier first audio.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

config.yaml

@@ -23,7 +23,7 @@ wyoming:
   host: "0.0.0.0"
   port: 10200
   # Max characters per synthesis chunk (split at sentence boundaries)
-  chunk_size: 300
+  chunk_size: 120
 
 paths:
   model_cache: /app/hf_cache