test(admin-v2): Phase 2 frontend tests — 61 tests for 5 pages

- Billing (13 tests): plan cards, prices, limits, usage bars, payment flow
- ScheduledTasks (16 tests): CRUD table, schedule/target types, color tags
- Knowledge (12 tests): 4 tabs, items/categories/search/analytics panels
- Roles (12 tests): roles + permission templates tabs
- ConfigSync (8 tests): sync log viewer with action labels

Fix: Knowledge.tsx missing </Select> and </Modal> closing tags (JSX parse error)
Fix: tests/setup.ts added ResizeObserver mock for ProTable compatibility

admin-v2/tests/setup.ts

@@ -40,4 +40,11 @@ beforeAll(() => {
       return {} as CSSStyleDeclaration
     }
   }
+
+  // Ant Design ProTable / rc-virtual-list require ResizeObserver
+  global.ResizeObserver = class ResizeObserver {
+    observe() {}
+    unobserve() {}
+    disconnect() {}
+  }
 })