fix: levels and categories empty due to res vs res.data mismatch

- Fix Classification.vue: levels use res.data, auto-fetch on mount
- Fix Task.vue: levels and categories use res.data
- Fix Project.vue: templates use res.data

frontend/src/views/project/Project.vue

@@ -215,7 +215,7 @@ async function handleDelete(p: ProjectItem) {
 async function fetchMeta() {
   try {
     const [tRes, sRes] = await Promise.all([getTemplates(), getDataSources()])
-    templates.value = (tRes as any) || []
+    templates.value = (tRes as any)?.data || []
     dataSources.value = (sRes as any)?.data || []
   } catch (e) {
     // ignore