🦝 Fix args being None in worker processes

**Problem:** Worker processes had `args = None` causing AttributeError
when accessing `args.xtts_device`, `args.use_deepspeed`, etc. This
broke all non-Piper TTS engines (Silero, Kokoro, XTTS).

**Root Cause:** `args` was parsed in `if __name__ == "__main__"` block
which only runs in parent process, not in uvicorn worker processes.

**Solution:** Created DefaultArgs class with sensible defaults for
worker processes. Main process still overrides these with actual
command-line arguments.

**Impact:** All TTS engines now work in worker processes.

🦝 Generated with [Claude Code](https://claude.com/claude-code)

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

speech.py

@@ -98,7 +98,19 @@ silero_model = None
 silero_speakers = {}
 kokoro_pipeline = None
 kokoro_lang = None
-args = None
+
+# Default args for worker processes (will be overridden in __main__)
+class DefaultArgs:
+    xtts_device = 'cpu'
+    use_deepspeed = False
+    unload_timer = None
+    log_level = 'INFO'
+    host = '0.0.0.0'
+    port = 8000
+    preload = None
+    no_cache_speaker = False
+
+args = DefaultArgs()
 
 # Voice-to-model lookup cache (loaded at startup)
 voice_to_model_cache = {}