feat: migrate to Better Auth for authentication, update environment variables, and enhance database schema with accounts and sessions

Backend/utils/jwt.ts

@@ -1,28 +0,0 @@
-import jwt from 'jsonwebtoken';
-
-const JWT_EXPIRES_IN = (process.env.JWT_EXPIRES_IN ?? '7d') as jwt.SignOptions['expiresIn'];
-
-function getJwtSecret(): string {
-  const secret = process.env.JWT_SECRET;
-
-  if (!secret) {
-    throw new Error('JWT_SECRET is not set');
-  }
-
-  return secret;
-}
-
-export type JwtPayload = {
-  userId: string;
-  email: string;
-};
-
-export function signAccessToken(payload: JwtPayload): string {
-  return jwt.sign(payload, getJwtSecret(), {
-    expiresIn: JWT_EXPIRES_IN,
-  });
-}
-
-export function verifyAccessToken(token: string): JwtPayload {
-  return jwt.verify(token, getJwtSecret()) as JwtPayload;
-}