feat: Add OpenAI-compatible TTS endpoint and engines

- Implements POST /v1/audio/speech endpoint (OpenAI API compatible).
- Integrates Kokoro and XTTS engines (including dependencies and implementations).
- Updates main application to register new engines and router.
- Adds unit tests for OpenAI compatibility.
- Updates requirements.txt for new engines.

app/main.py

@@ -20,15 +20,28 @@ import os
 import base64
 import shutil
 import uvicorn
+import logging
 
 from app.config import settings
 from app.engines.piper import PiperEngine
 from app.engines.styletts import StyleTTSEngine
 from app.engines.chattts import ChatTTSEngine
 from app.engines.f5_tts import F5TTSEngine
+from app.engines.kokoro import KokoroEngine
+from app.engines.xtts import XTTSEngine
 from app.utils.text import chunk_text
 from app.utils.audio import concat_audio
 from app.utils.cache import build_cache_key
+from app.routers import openai_compatible
+
+# Configure logging based on settings
+logging.basicConfig(level=settings.LOG_LEVEL, format='%(asctime)s - %(name)s - %(levelname)s - %(message)s')
+logger = logging.getLogger(__name__)
+
+# Explicitly configure uvicorn loggers
+logging.getLogger("uvicorn.access").setLevel(settings.LOG_LEVEL)
+logging.getLogger("uvicorn.error").setLevel(settings.LOG_LEVEL)
+logging.getLogger("uvicorn.server").setLevel(settings.LOG_LEVEL)
 
 # --- Master list of all possible engine classes. ---
 ALL_ENGINES = {
@@ -36,6 +49,8 @@ ALL_ENGINES = {
     "styletts": StyleTTSEngine,
     "chattts": ChatTTSEngine,
     "f5-tts": F5TTSEngine,
+    "kokoro": KokoroEngine,
+    "xtts": XTTSEngine,
 }
 
 def create_app():
@@ -50,14 +65,17 @@ def create_app():
     app.ENGINE_REGISTRY = {}
     for engine_name in settings.ACTIVE_ENGINES:
         if engine_name in ALL_ENGINES:
-            print(f"Activating engine: {engine_name}")
+            logger.info(f"Activating engine: {engine_name}")
             app.ENGINE_REGISTRY[engine_name] = ALL_ENGINES[engine_name]()
         else:
-            print(f"Warning: Engine '{engine_name}' requested in config but not found in ALL_ENGINES.")
+            logger.warning(f"Engine '{engine_name}' requested in config but not found in ALL_ENGINES.")
 
     # Ensure the audio asset/cache directory exists.
     os.makedirs(settings.AUDIO_CACHE_DIR, exist_ok=True)
 
+    # Register Routers
+    app.include_router(openai_compatible.router)
+
     class TTSRequest(BaseModel):
         text: str
         engine: str
@@ -197,6 +215,10 @@ def create_app():
         On startup, check for the existence of the models directory.
         This helps prevent race conditions with volume mounts.
         """
+        if os.getenv("SKIP_MODEL_CHECK", "false").lower() == "true":
+            logger.info("Skipping model directory check (SKIP_MODEL_CHECK=true)")
+            return
+
         model_path = "/models/piper"
         max_retries = 10
         retry_delay = 2  # seconds