docs: add JSDoc to useDebounce hook

web/client/src/App.jsx

@@ -7,6 +7,10 @@ import Categories from "./pages/Categories";
 import About from "./pages/About";
 import Recommend from "./pages/Recommend";
 
+/**
+ * Main application router.
+ * Renders layout with Navbar/Footer and routes to pages.
+ */
 export default function App() {
   return (
     <>

web/client/src/components/Navbar.jsx

@@ -9,6 +9,9 @@ const NAV_LINKS = [
   { label: "About", to: "/about" },
 ];
 
+/**
+ * Site navigation bar with responsive menu.
+ */
 export default function Navbar() {
   const [open, setOpen] = useState(false);
   const { pathname } = useLocation();

web/client/src/hooks/useDebounce.js

@@ -1,5 +1,11 @@
 import { useState, useEffect } from "react";
 
+/**
+ * Debounces a value to delay updates (e.g., for search input).
+ * @param {any} value - The value to debounce.
+ * @param {number} delay - Delay in ms (default 300).
+ * @returns {any} The debounced value.
+ */
 export function useDebounce(value, delay = 300) {
   const [debounced, setDebounced] = useState(value);
   useEffect(() => {