feat: internationalize API error responses by locale

Add shared error codes with zh/en/ms messages, coded app exceptions,
and locale-aware global filter. Frontends send X-Locale so error text
matches the active UI language.

Co-authored-by: Cursor <cursoragent@cursor.com>

packages/shared/src/index.ts

@@ -126,4 +126,8 @@ export interface ApiResponse<T = unknown> {
   data?: T;
   message?: string;
   error?: string;
+  code?: string;
+  params?: Record<string, string | number> | null;
 }
+
+export * from './api-errors';