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/ToastContext.tsx

@@ -0,0 +1,83 @@
+import React, { createContext, useContext, useState, ReactNode, useEffect } from 'react';
+import Toast, { ToastType } from '../components/Toast';
+import { registerToastHandler } from '../src/utils/toast';
+
+interface ToastItem {
+  id: string;
+  type: ToastType;
+  title?: string;
+  message: string;
+  duration?: number;
+}
+
+interface ToastContextType {
+  showToast: (type: ToastType, message: string, title?: string, duration?: number) => void;
+  showSuccess: (message: string, title?: string) => void;
+  showError: (message: string, title?: string) => void;
+  showWarning: (message: string, title?: string) => void;
+  showInfo: (message: string, title?: string) => void;
+}
+
+const ToastContext = createContext<ToastContextType | undefined>(undefined);
+
+export const useToast = () => {
+  const context = useContext(ToastContext);
+  if (!context) {
+    throw new Error('useToast must be used within a ToastProvider');
+  }
+  return context;
+};
+
+interface ToastProviderProps {
+  children: ReactNode;
+}
+
+export const ToastProvider: React.FC<ToastProviderProps> = ({ children }) => {
+  const [toasts, setToasts] = useState<ToastItem[]>([]);
+
+  const showToast = (type: ToastType, message: string, title?: string, duration?: number) => {
+    const id = Date.now().toString();
+    const newToast: ToastItem = { id, type, message, title, duration };
+
+    setToasts(prev => {
+      // Deduplicate identical messages: discard old one if current type and content are the same
+      const filtered = prev.filter(t => t.message !== message || t.type !== type);
+      return [...filtered, newToast];
+    });
+  };
+
+  useEffect(() => {
+    registerToastHandler({ showToast });
+  }, []);
+
+  const removeToast = (id: string) => {
+    setToasts(prev => prev.filter(toast => toast.id !== id));
+  };
+
+  const showSuccess = (message: string, title?: string) => showToast('success', message, title);
+  const showError = (message: string, title?: string) => showToast('error', message, title);
+  const showWarning = (message: string, title?: string) => showToast('warning', message, title);
+  const showInfo = (message: string, title?: string) => showToast('info', message, title);
+
+  return (
+    <ToastContext.Provider value={{ showToast, showSuccess, showError, showWarning, showInfo }}>
+      {children}
+      <div className="fixed bottom-0 right-0 z-[9999] p-4 space-y-3 pointer-events-none w-full max-w-sm flex flex-col items-end">
+        {toasts.map((toast) => (
+          <div
+            key={toast.id}
+            className="pointer-events-auto w-full"
+          >
+            <Toast
+              type={toast.type}
+              title={toast.title}
+              message={toast.message}
+              duration={toast.duration}
+              onClose={() => removeToast(toast.id)}
+            />
+          </div>
+        ))}
+      </div>
+    </ToastContext.Provider>
+  );
+};