feat: add authentication and admin features

- Added `jose` library for JWT token generation and verification.
- Implemented login functionality with token storage using cookies.
- Created `HeaderAdmin` component for admin panel with login/logout capabilities.
- Developed `LoginForm` component for user authentication.
- Added `Table` component to display data with caching from localStorage.
- Introduced `SubHeaderAdmin` for additional admin actions.
- Enhanced `database.js` with functions for admin login and fetching table data.
- Updated `server.js` to handle new routes for login and table data retrieval.
- Modified `package.json` and `package-lock.json` to include new dependencies.

backend/services/tokenService.js

@@ -0,0 +1,26 @@
+import { SignJWT, jwtVerify } from "jose";
+import env from "dotenv";
+env.config();
+const secret = new TextEncoder().encode(process.env.SECRET_KEY);
+
+export async function generateToken(payload) {
+  const newToken = await new SignJWT(payload)
+    .setProtectedHeader({ alg: "HS256" })
+    .setIssuedAt()
+    .setExpirationTime("2h") // Token valid for 2 hours
+    .sign(secret);
+  console.log("Generated token: ", newToken);
+  return newToken;
+}
+
+export async function authenticate(req, res, next) {
+  const authHeader = req.headers["authorization"];
+  const token = authHeader && authHeader.split(" ")[1]; // Bearer <token>
+
+  if (token == null) return res.sendStatus(401); // No token present
+
+  const { payload } = await jwtVerify(token, secret);
+  req.user = payload;
+
+  next();
+}