Update app.py

app.py

@@ -35,10 +35,11 @@ HF_TOKEN = os.getenv("HF_TOKEN")
 if HF_TOKEN:
     print("🔑 Logging in to Hugging Face Hub...")
     login(HF_TOKEN)
-    
-engines = {}
-voices = {}
+
+engines: dict[str, "BaseEngine"] = {}
+voices:  dict[str, list]        = {}
 current_engine = None
+
 play_text_to_speech_semaphore = threading.Semaphore(1)
 
 PORT = int(os.getenv("TTS_FASTAPI_PORT", 7860))   # Zahl kongruent halten