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

frontend/src/views/category/Category.vue

@@ -236,7 +236,7 @@ const ruleRules = {
 async function fetchLevels() {
   try {
     const res: any = await getDataLevels()
-    levels.value = res || []
+    levels.value = res.data || []
   } catch (e: any) {
     ElMessage.error(e?.message || '加载分级失败')
   }
@@ -245,7 +245,7 @@ async function fetchLevels() {
 async function fetchCategories() {
   try {
     const res: any = await getCategoryTree()
-    categoryTree.value = res || []
+    categoryTree.value = res.data || []
   } catch (e: any) {
     ElMessage.error(e?.message || '加载分类失败')
   }
@@ -267,7 +267,7 @@ async function fetchRules() {
 async function fetchTemplates() {
   try {
     const res: any = await getTemplates()
-    templates.value = res || []
+    templates.value = res.data || []
   } catch (e: any) {
     // ignore
   }

frontend/src/views/classification/Classification.vue

@@ -75,8 +75,7 @@ import { ref, onMounted } from 'vue'
 import { ElMessage } from 'element-plus'
 import { Search } from '@element-plus/icons-vue'
 import { getProjects } from '@/api/project'
-import { getDataLevels } from '@/api/classification'
-import { getTaskItems } from '@/api/task'
+import { getDataLevels, getClassificationResults } from '@/api/classification'
 
 const loading = ref(false)
 const resultList = ref<any[]>([])
@@ -100,16 +99,15 @@ function confidenceClass(v: number) {
 async function fetchData() {
   loading.value = true
   try {
-    if (!filterProjectId.value) {
-      resultList.value = []
-      total.value = 0
-      return
-    }
-    const res: any = await getTaskItems(-1) // use a special endpoint or fetch from project
-    // Actually we need a dedicated results API. For now, fetch all items for project via task workaround
-    // In real implementation, call: GET /api/v1/projects/{id}/results
-    resultList.value = []
-    total.value = 0
+    const res: any = await getClassificationResults({
+      project_id: filterProjectId.value || undefined,
+      level_id: filterLevelId.value || undefined,
+      keyword: filterKeyword.value || undefined,
+      page: page.value,
+      page_size: pageSize.value,
+    })
+    resultList.value = res.data || []
+    total.value = res.total || 0
   } catch (e: any) {
     ElMessage.error(e?.message || '加载失败')
   } finally {

frontend/src/views/metadata/Metadata.vue

@@ -118,7 +118,7 @@ function filterNode(value: string, data: TreeNode) {
 async function fetchTree() {
   try {
     const res: any = await getMetadataTree()
-    treeData.value = res || []
+    treeData.value = res.data || []
   } catch (e: any) {
     ElMessage.error(e?.message || '加载失败')
   }

frontend/src/views/task/Task.vue

@@ -150,7 +150,7 @@ const filteredLabelItems = computed(() => {
 async function fetchData() {
   try {
     const res: any = await getMyTasks()
-    tasks.value = res || []
+    tasks.value = res.data || []
   } catch (e: any) {
     ElMessage.error(e?.message || '加载失败')
   }
@@ -186,7 +186,7 @@ async function openLabel(task: TaskItem) {
   }
   try {
     const res: any = await getTaskItems(task.id)
-    labelItems.value = (res || []).map((item: any) => ({
+    labelItems.value = (res.data || []).map((item: any) => ({
       ...item,
       _category_id: item.category_id,
       _level_id: item.level_id,