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.py

@@ -29,7 +29,7 @@ DEFAULTS = {
     "wyoming": {
         "host": "0.0.0.0",
         "port": 10200,
-        "chunk_size": 300,
+        "chunk_size": 120,
     },
     "paths": {
         "model_cache": "/app/hf_cache",