fix: convert effect values to proper types when loading from preferences

JSON stores numbers as strings, so pitch and speed were being returned
as strings from get_user_effects(), causing format string errors like:
'Unknown format code d for object of type str'

Now get_user_effects() explicitly converts:
- pitch to int
- speed to float

This fixes the format string errors when logging or displaying effects.

voice_manager.py

@@ -195,12 +195,15 @@ class VoiceManager:
 
     # Effects management methods
 
-    def get_user_effects(self, user_id: int) -> dict[str, Any]:
+    def get_user_effects(self, user_id: int) -> dict[str, int | float]:
         """Get the audio effects for a user. Returns defaults if not set."""
         effects = self._user_effects.get(user_id, {})
+        # Convert to proper types (JSON stores them as strings)
+        pitch = effects.get("pitch", AudioEffects.PITCH_DEFAULT)
+        speed = effects.get("speed", AudioEffects.SPEED_DEFAULT)
         return {
-            "pitch": effects.get("pitch", AudioEffects.PITCH_DEFAULT),
-            "speed": effects.get("speed", AudioEffects.SPEED_DEFAULT),
+            "pitch": int(pitch) if pitch is not None else AudioEffects.PITCH_DEFAULT,
+            "speed": float(speed) if speed is not None else AudioEffects.SPEED_DEFAULT,
         }
 
     def set_user_effect(self, user_id: int, effect_name: str, value: Any) -> tuple[bool, str]: