feat(tests): enhance test coverage with integration and utility tests

- Updated QueueCard tests to use getAllByText for better resilience against multiple occurrences.
- Modified useCodexLens tests to check for error existence instead of specific message.
- Added mock for ResizeObserver in test setup to support components using it.
- Introduced integration tests for appStore and hooks interactions, covering locale and theme flows.
- Created layout-utils tests to validate pane manipulation functions.
- Added queryKeys tests to ensure correct key generation for workspace queries.
- Implemented utils tests for class name merging and memory metadata parsing.

ccw/frontend/src/test/setup.ts

@@ -60,3 +60,16 @@ Element.prototype.scrollIntoView = vi.fn();
 Element.prototype.hasPointerCapture = vi.fn(() => false);
 Element.prototype.setPointerCapture = vi.fn();
 Element.prototype.releasePointerCapture = vi.fn();
+
+// Mock ResizeObserver for components that use it (e.g., recharts, allotment)
+class ResizeObserverMock {
+  observe = vi.fn();
+  unobserve = vi.fn();
+  disconnect = vi.fn();
+}
+
+Object.defineProperty(global, 'ResizeObserver', {
+  writable: true,
+  configurable: true,
+  value: ResizeObserverMock,
+});