refactor: update model version in Gemini AI Service and optimize transcript fetching in YouTube Service

app/routes/commend/gemini_service.py

@@ -97,7 +97,7 @@ Rules: 1-2 sentences, natural, specific to video, max 1 emoji.
 Comment:"""
 
         response = client.models.generate_content(
-            model="gemini-1.5-flash",
+            model="gemini-2.5-flash-lite",
             contents=prompt
         )
 

app/routes/commend/youtube_service.py

@@ -233,22 +233,16 @@ def get_video_transcript(video_id: str) -> Tuple[Optional[str], Optional[str]]:
     try:
         from youtube_transcript_api import YouTubeTranscriptApi
 
-        transcript_list = YouTubeTranscriptApi.list_transcripts(video_id)
-
-        # Dil önceliği: tr -> en -> auto
-        for lang in ['tr', 'en']:
-            try:
-                transcript = transcript_list.find_transcript([lang])
-                break
-            except:
-                continue
-        else:
+        # Yeni API: doğrudan get_transcript kullan
+        try:
+            transcript_data = YouTubeTranscriptApi.get_transcript(video_id, languages=['tr', 'en'])
+        except Exception:
+            # Otomatik oluşturulan altyazıyı dene
             try:
-                transcript = transcript_list.find_generated_transcript(['tr', 'en'])
-            except:
+                transcript_data = YouTubeTranscriptApi.get_transcript(video_id)
+            except Exception:
                 return None, "No transcript available"
 
-        transcript_data = transcript.fetch()
         full_text = ' '.join([entry['text'] for entry in transcript_data])
 
         # Token limiti için kısalt