Fix: Kling Motion set status to 'completed' to match frontend poll check

src/content_engine/api/routes_video.py

@@ -374,7 +374,7 @@ async def _generate_kling_motion_video(
                 r = await dl_client.get(video_url_out)
                 output_path.write_bytes(r.content)
 
-            _video_jobs[job_id]["status"] = "done"
+            _video_jobs[job_id]["status"] = "completed"
             _video_jobs[job_id]["filename"] = filename
             _video_jobs[job_id]["message"] = "Done"
             logger.info("Kling Motion video saved: %s", filename)