feat: add Zustand stores and custom hooks

frontend-mobile/hooks/useAuth.ts

@@ -0,0 +1,19 @@
+import { useEffect } from 'react';
+import { useAuthStore } from '../store/authStore';
+
+export function useAuth() {
+  const { user, isLoading, isAuthenticated, login, logout, checkAuth } = useAuthStore();
+
+  useEffect(() => {
+    checkAuth();
+  }, []);
+
+  return {
+    user,
+    isLoading,
+    isAuthenticated,
+    login,
+    logout,
+    isAdmin: user?.is_admin ?? false,
+  };
+}

frontend-mobile/hooks/useDebounce.ts

@@ -0,0 +1,17 @@
+import { useState, useEffect } from 'react';
+
+export function useDebounce<T>(value: T, delay: number): T {
+  const [debouncedValue, setDebouncedValue] = useState<T>(value);
+
+  useEffect(() => {
+    const timer = setTimeout(() => {
+      setDebouncedValue(value);
+    }, delay);
+
+    return () => {
+      clearTimeout(timer);
+    };
+  }, [value, delay]);
+
+  return debouncedValue;
+}