feat: Add retry logic for Typecast API (3 retries with exponential backoff)

tts.py

@@ -445,8 +445,10 @@ def predict_humelo_tts(text: str, voice: str = "리아", emotion: str = "neutral
         return f.name
 
 
-def predict_typecast_tts(text: str, voice_id: str, model: str = "ssfm-v30") -> str:
-    """Typecast TTS API 호출 (v3.0 experiment API)"""
+def predict_typecast_tts(text: str, voice_id: str, model: str = "ssfm-v30", max_retries: int = 3) -> str:
+    """Typecast TTS API 호출 (v3.0 experiment API) with retry logic"""
+    import time
+    
     api_key = TYPECAST_API_KEY
     if not api_key:
         raise ValueError("TYPECAST_API_KEY 환경 변수가 설정되지 않았습니다.")
@@ -464,12 +466,24 @@ def predict_typecast_tts(text: str, voice_id: str, model: str = "ssfm-v30") -> s
         "Content-Type": "application/json"
     }
     
-    response = requests.post(url, headers=headers, json=payload, timeout=60)
-    response.raise_for_status()
-    
-    with tempfile.NamedTemporaryFile(delete=False, suffix=".wav") as f:
-        f.write(response.content)
-        return f.name
+    last_error = None
+    for attempt in range(max_retries):
+        try:
+            response = requests.post(url, headers=headers, json=payload, timeout=60)
+            response.raise_for_status()
+            
+            with tempfile.NamedTemporaryFile(delete=False, suffix=".wav") as f:
+                f.write(response.content)
+                return f.name
+        except requests.exceptions.RequestException as e:
+            last_error = e
+            print(f"[Typecast] Attempt {attempt + 1}/{max_retries} failed: {e}")
+            if attempt < max_retries - 1:
+                wait_time = (attempt + 1) * 2  # 2초, 4초, 6초...
+                print(f"[Typecast] Retrying in {wait_time}s...")
+                time.sleep(wait_time)
+    
+    raise ValueError(f"Typecast TTS API 오류 (재시도 {max_retries}회 실패): {last_error}")
 
 
 def predict_gemini_tts(text: str, voice: str = "Aoede", model: str = "gemini-2.5-flash-tts") -> str: