feat: Integrate IndexTTS2 model and update related schemas and frontend components

qwen3-tts-backend/api/audiobook.py

@@ -53,6 +53,7 @@ def _project_to_detail(project, db: Session) -> AudiobookProjectDetail:
             description=c.description,
             instruct=c.instruct,
             voice_design_id=c.voice_design_id,
+            use_indextts2=c.use_indextts2 or False,
         )
         for c in (project.characters or [])
     ]
@@ -415,6 +416,7 @@ async def update_character(
         description=data.description,
         instruct=data.instruct,
         voice_design_id=data.voice_design_id,
+        use_indextts2=data.use_indextts2,
     )
 
     if data.instruct is not None and char.voice_design_id:
@@ -431,6 +433,7 @@ async def update_character(
         description=char.description,
         instruct=char.instruct,
         voice_design_id=char.voice_design_id,
+        use_indextts2=char.use_indextts2 or False,
     )