feat(storyboard): persist scene refs and video prompts

yaoai-comic-studio/yaoai-api/src/main/java/com/yaoai/api/controller/StoryboardController.java

@@ -98,7 +98,7 @@ public class StoryboardController {
     public ApiResponse<Map<String, String>> generatePrompt(@PathVariable Long projectId,
                                                            @PathVariable Long storyboardId) {
         Long tenantId = TenantContext.get();
-        String prompt = storyboardService.generatePrompt(storyboardId, tenantId);
-        return ApiResponse.success(Map.of("prompt", prompt));
+        Map<String, String> body = Map.of("prompt", storyboardService.generatePrompt(storyboardId, tenantId));
+        return ApiResponse.success(body);
     }
 }

yaoai-comic-studio/yaoai-pipeline/src/main/java/com/yaoai/pipeline/service/StoryboardPipelineService.java

@@ -30,4 +30,6 @@ public interface StoryboardPipelineService {
      * AI 根据分镜剧本信息生成视频描述提示词（分时段影视风格）
      */
     String generatePrompt(Long storyboardId, Long tenantId);
+
+    List<Storyboard> populateMissingVideoPromptsByEpisode(Long episodeId, Long tenantId);
 }