Add E2E tests for internationalization across multiple pages

- Implemented navigation.spec.ts to test language switching and translation of navigation elements.
- Created sessions-page.spec.ts to verify translations on the sessions page, including headers, status badges, and date formatting.
- Developed settings-page.spec.ts to ensure settings page content is translated and persists across sessions.
- Added skills-page.spec.ts to validate translations for skill categories, action buttons, and empty states.

ccw/frontend/src/locales/zh/index.ts

@@ -0,0 +1,64 @@
+/**
+ * Chinese (Simplified) translations
+ * Consolidated exports for all Chinese translation files
+ */
+
+import common from './common.json';
+import navigation from './navigation.json';
+import sessions from './sessions.json';
+import issues from './issues.json';
+import home from './home.json';
+import orchestrator from './orchestrator.json';
+import loops from './loops.json';
+import commands from './commands.json';
+import memory from './memory.json';
+import settings from './settings.json';
+import fixSession from './fix-session.json';
+import history from './history.json';
+import liteTasks from './lite-tasks.json';
+import projectOverview from './project-overview.json';
+import reviewSession from './review-session.json';
+import sessionDetail from './session-detail.json';
+
+/**
+ * Flattens nested JSON object to dot-separated keys
+ * e.g., { actions: { save: 'Save' } } => { 'actions.save': 'Save' }
+ */
+function flattenMessages(obj: Record<string, unknown>, prefix = ''): Record<string, string> {
+  const result: Record<string, string> = {};
+
+  for (const key in obj) {
+    const fullKey = prefix ? `${prefix}.${key}` : key;
+    const value = obj[key];
+
+    if (typeof value === 'object' && value !== null && !Array.isArray(value)) {
+      Object.assign(result, flattenMessages(value as Record<string, unknown>, fullKey));
+    } else if (typeof value === 'string') {
+      result[fullKey] = value;
+    }
+  }
+
+  return result;
+}
+
+/**
+ * Consolidated and flattened Chinese messages
+ */
+export default {
+  ...flattenMessages(common),
+  ...flattenMessages(navigation),
+  ...flattenMessages(sessions),
+  ...flattenMessages(issues),
+  ...flattenMessages(home),
+  ...flattenMessages(orchestrator),
+  ...flattenMessages(loops),
+  ...flattenMessages(commands),
+  ...flattenMessages(memory),
+  ...flattenMessages(settings),
+  ...flattenMessages(fixSession),
+  ...flattenMessages(history),
+  ...flattenMessages(liteTasks),
+  ...flattenMessages(projectOverview),
+  ...flattenMessages(reviewSession),
+  ...flattenMessages(sessionDetail),
+} as Record<string, string>;