feat: implement QuestionBank CRUD with pagination and template query

- Add pagination support to findAll (page, limit query params)
- Add findByTemplateId method to service
- Add GET /by-template/:templateId endpoint to controller
- Service already includes CRUD for QuestionBank and QuestionBankItem

web/contexts/LanguageContext.tsx

@@ -0,0 +1,46 @@
+import React from 'react';
+import { translations, Language } from '../utils/translations';
+
+interface LanguageContextType {
+  language: Language;
+  setLanguage: (lang: Language) => void;
+  t: (key: keyof typeof translations['zh'], ...args: any[]) => string;
+}
+
+const LanguageContext = React.createContext<LanguageContextType | undefined>(undefined);
+
+export const LanguageProvider: React.FC<{ children: React.ReactNode }> = ({ children }) => {
+  const [language, setLanguage] = React.useState<Language>(() => {
+    const saved = localStorage.getItem('userLanguage');
+    return (saved as Language) || 'zh';
+  });
+
+  const handleSetLanguage = (lang: Language) => {
+    setLanguage(lang);
+    localStorage.setItem('userLanguage', lang);
+  };
+
+  const t = (key: keyof typeof translations['zh'], ...args: any[]) => {
+    let str = translations[language][key] || key;
+    if (args.length > 0) {
+      args.forEach((arg, i) => {
+        str = str.replace(new RegExp(`\\$${i + 1}`, 'g'), String(arg));
+      });
+    }
+    return str;
+  };
+
+  return React.createElement(
+    LanguageContext.Provider,
+    { value: { language, setLanguage: handleSetLanguage, t } },
+    children
+  );
+};
+
+export const useLanguage = () => {
+  const context = React.useContext(LanguageContext);
+  if (!context) {
+    throw new Error('useLanguage must be used within a LanguageProvider');
+  }
+  return context;
+};