feat: Implement video generation functionality and integrate with Kling API.

api/models/GenerationRequest.py

@@ -27,6 +27,7 @@ class GenerationsResponse(BaseModel):
 class GenerationResponse(BaseModel):
     id: str
     status: GenerationStatus
+    gen_type: GenType = GenType.IMAGE
     failed_reason: Optional[str] = None
     
     linked_character_id: Optional[str] = None
@@ -45,6 +46,10 @@ class GenerationResponse(BaseModel):
     progress: int = 0
     cost: Optional[float] = None
     created_by: Optional[str] = None
+    # Video-specific
+    kling_task_id: Optional[str] = None
+    video_duration: Optional[int] = None
+    video_mode: Optional[str] = None
     created_at: datetime = datetime.now(UTC)
     updated_at: datetime = datetime.now(UTC)