feat: queue voice session cover generation jobs

backend/tests/test_voice_sessions.py

@@ -99,9 +99,9 @@ async def test_voice_session_correct_turn_and_finalize_to_story(
             new_callable=AsyncMock,
         ) as mock_tts,
         patch(
-            "app.services.voice_session_service.generate_story_cover",
+            "app.services.voice_session_service.queue_story_asset_generation",
             new_callable=AsyncMock,
-        ) as mock_generate_cover,
+        ) as mock_queue_asset_generation,
     ):
         mock_generate.side_effect = [
             StoryOutput(
@@ -118,7 +118,23 @@ async def test_voice_session_correct_turn_and_finalize_to_story(
             ),
         ]
         mock_tts.side_effect = [b"turn-1-audio", b"turn-2-audio"]
-        mock_generate_cover.return_value = "https://example.com/voice-cover.png"
+        mock_queue_asset_generation.return_value = {
+            "id": "cover-job-123",
+            "story_id": 1,
+            "output_mode": "asset_generation",
+            "input_type": "image",
+            "status": "running",
+            "current_step": "request_accepted",
+            "progress_percent": 5,
+            "progress_label": "已接收请求",
+            "is_terminal": False,
+            "can_cancel": True,
+            "can_retry": False,
+            "result_snapshot": {},
+            "error_message": None,
+            "created_at": "2026-04-20T00:00:00Z",
+            "updated_at": "2026-04-20T00:00:00Z",
+        }
 
         transport = ASGITransport(app=app)
         try:
@@ -156,6 +172,7 @@ async def test_voice_session_correct_turn_and_finalize_to_story(
                 finalize_data = response.json()
                 story_id = finalize_data["story_id"]
                 assert finalize_data["status"] == "completed"
+                assert finalize_data["generation_job_id"] == "cover-job-123"
 
                 response = await client.get(f"/api/stories/{story_id}")
                 assert response.status_code == 200
@@ -172,7 +189,7 @@ async def test_voice_session_correct_turn_and_finalize_to_story(
                 assert session_data["final_story_id"] == story_id
                 assert session_data["can_continue"] is False
                 assert session_data["story_state"]["final_summary"]
-                mock_generate_cover.assert_awaited_once()
+                mock_queue_asset_generation.assert_awaited_once()
         finally:
             app.dependency_overrides.clear()