feat(auth): implement user authentication with JWT and NextAuth

- Added user registration and login functionality with JWT authentication.
- Created auth controller, service, and module in the backend.
- Implemented user model and user products management.
- Integrated NextAuth for session management on the frontend.
- Added middleware for protecting routes and handling public access.
- Updated frontend API routes to include authorization headers.
- Enhanced recipe and user product models to support ownership and visibility.
- Created registration and login pages in the frontend.
- Added necessary types for NextAuth session management.

backend/src/auth/auth.controller.ts

@@ -0,0 +1,23 @@
+import { Controller, Post, Body, HttpCode, HttpStatus } from '@nestjs/common';
+import { AuthService } from './auth.service';
+import { RegisterDto } from './dto/register.dto';
+import { LoginDto } from './dto/login.dto';
+import { Public } from './decorators/public.decorator';
+
+@Controller('auth')
+export class AuthController {
+  constructor(private readonly authService: AuthService) {}
+
+  @Public()
+  @Post('register')
+  register(@Body() dto: RegisterDto) {
+    return this.authService.register(dto);
+  }
+
+  @Public()
+  @HttpCode(HttpStatus.OK)
+  @Post('login')
+  login(@Body() dto: LoginDto) {
+    return this.authService.login(dto);
+  }
+}