test: expand frontend test suite to 82% coverage

Adds ~45 new and updated test files covering Admin, Collab, Dashboard, Map, Memories, PDF, Photos, Planner, Settings, Vacay, Weather components, pages, stores, and a WebSocket integration test.

client/tests/unit/stores/settingsStore.test.ts

@@ -79,4 +79,110 @@ describe('settingsStore', () => {
       expect(state.isLoaded).toBe(true);
     });
   });
+
+  describe('FE-STORE-SETTINGS-006: setLanguageLocal updates state and localStorage', () => {
+    it('sets language in state and localStorage without an API call', () => {
+      useSettingsStore.getState().setLanguageLocal('ja');
+
+      const state = useSettingsStore.getState();
+      expect(state.settings.language).toBe('ja');
+      expect(localStorage.getItem('app_language')).toBe('ja');
+    });
+  });
+
+  describe('FE-STORE-SETTINGS-007: setLanguageLocal without prior localStorage value', () => {
+    it('writes to localStorage even when no prior value exists', () => {
+      localStorage.clear();
+
+      useSettingsStore.getState().setLanguageLocal('ko');
+
+      const state = useSettingsStore.getState();
+      expect(state.settings.language).toBe('ko');
+      expect(localStorage.getItem('app_language')).toBe('ko');
+    });
+  });
+
+  describe('FE-STORE-SETTINGS-008: updateSettings bulk update', () => {
+    it('updates multiple settings keys and calls bulk API', async () => {
+      await useSettingsStore.getState().updateSettings({ dark_mode: true, default_currency: 'JPY' });
+
+      const state = useSettingsStore.getState();
+      expect(state.settings.dark_mode).toBe(true);
+      expect(state.settings.default_currency).toBe('JPY');
+    });
+  });
+
+  describe('FE-STORE-SETTINGS-009: updateSettings optimistic update', () => {
+    it('updates state synchronously before API resolves', async () => {
+      const promise = useSettingsStore.getState().updateSettings({ dark_mode: true });
+
+      expect(useSettingsStore.getState().settings.dark_mode).toBe(true);
+
+      await promise;
+    });
+  });
+
+  describe('FE-STORE-SETTINGS-010: updateSettings API failure throws', () => {
+    it('throws when bulk API returns 500', async () => {
+      server.use(
+        http.post('/api/settings/bulk', () =>
+          HttpResponse.json({ error: 'Server error' }, { status: 500 })
+        )
+      );
+
+      await expect(
+        useSettingsStore.getState().updateSettings({ dark_mode: true })
+      ).rejects.toThrow();
+    });
+  });
+
+  describe('FE-STORE-SETTINGS-011: updateSetting non-language key does not write to localStorage', () => {
+    it('does not modify app_language in localStorage', async () => {
+      const before = localStorage.getItem('app_language');
+
+      await useSettingsStore.getState().updateSetting('dark_mode', true);
+
+      expect(localStorage.getItem('app_language')).toBe(before);
+    });
+  });
+
+  describe('FE-STORE-SETTINGS-012: loadSettings merges server values with defaults', () => {
+    it('preserves default keys not returned by server', async () => {
+      server.use(
+        http.get('/api/settings', () =>
+          HttpResponse.json({ settings: { dark_mode: true } })
+        )
+      );
+
+      await useSettingsStore.getState().loadSettings();
+
+      const state = useSettingsStore.getState();
+      expect(state.settings.dark_mode).toBe(true);
+      expect(state.settings.default_currency).toBe('USD');
+    });
+  });
+
+  describe('FE-STORE-SETTINGS-013: updateSetting for time_format', () => {
+    it('updates time_format in state', async () => {
+      await useSettingsStore.getState().updateSetting('time_format', '24h');
+
+      expect(useSettingsStore.getState().settings.time_format).toBe('24h');
+    });
+  });
+
+  describe('FE-STORE-SETTINGS-014: updateSetting API failure leaves optimistic state', () => {
+    it('throws on API failure but keeps the optimistic state', async () => {
+      server.use(
+        http.put('/api/settings', () =>
+          HttpResponse.json({ error: 'Server error' }, { status: 500 })
+        )
+      );
+
+      await expect(
+        useSettingsStore.getState().updateSetting('default_zoom', 15)
+      ).rejects.toThrow();
+
+      expect(useSettingsStore.getState().settings.default_zoom).toBe(15);
+    });
+  });
 });