fix: classification results empty and res.data access issues

Backend:
- Add GET /classifications/results endpoint with project/level/keyword filters
- Add column relationship to ClassificationResult model
- Fix test data generator to fetch column IDs from DB after bulk insert

Frontend:
- Fix request.ts interceptor to return full response body (keep total/pagination)
- Fix all pages to use res.data instead of res
- Add getClassificationResults API in classification.ts
- Implement fetchData in Classification.vue with proper filtering and pagination
- Fix same res.data issue in Category.vue, Metadata.vue, Project.vue, DataSource.vue, Dashboard.vue, Task.vue

frontend/src/api/classification.ts

@@ -76,3 +76,34 @@ export function deleteRule(id: number) {
 export function getTemplates() {
   return request.get('/classifications/templates')
 }
+
+export interface ClassificationResultItem {
+  id: number
+  project_id: number
+  column_id?: number
+  column_name?: string
+  data_type?: string
+  comment?: string
+  table_name?: string
+  database_name?: string
+  source_name?: string
+  category_id?: number
+  category_name?: string
+  level_id?: number
+  level_name?: string
+  level_color?: string
+  source: string
+  confidence: number
+  status: string
+  created_at?: string
+}
+
+export function getClassificationResults(params: {
+  project_id?: number
+  level_id?: number
+  keyword?: string
+  page?: number
+  page_size?: number
+}) {
+  return request.get('/classifications/results', { params })
+}

frontend/src/api/request.ts

@@ -26,7 +26,7 @@ request.interceptors.response.use(
       ElMessage.error(res.message || '请求失败')
       return Promise.reject(new Error(res.message))
     }
-    return res.data
+    return res
   },
   (error: AxiosError) => {
     const status = error.response?.status