feat: add authentication routes, update environment variables, and enhance error handling

Backend/README.md

@@ -18,6 +18,9 @@ Set:
 
 ```bash
 DATABASE_URL=postgres://username:password@localhost:5432/database_name
+JWT_SECRET=replace_with_a_long_random_secret
+JWT_EXPIRES_IN=7d
+PORT=3000
 ```
 
 ## Run app
@@ -45,3 +48,33 @@ Open Drizzle Studio:
 ```bash
 bun run db:studio
 ```
+
+## Auth API
+
+Register:
+
+```bash
+POST /auth/register
+{
+  "email": "user@example.com",
+  "password": "password123",
+  "name": "User Name"
+}
+```
+
+Login:
+
+```bash
+POST /auth/login
+{
+  "email": "user@example.com",
+  "password": "password123"
+}
+```
+
+Get current user:
+
+```bash
+GET /auth/me
+Authorization: Bearer <token>
+```