feat: implement AuthModule with authentication and RBAC features

Added AuthModule with services, controllers, and guards for authentication. Implements session management, role-based access control, 2FA, and DTOs for user login, registration, and token refresh.

backend/src/auth/guards/auth.guard.ts

@@ -0,0 +1,44 @@
+import {
+	CanActivate,
+	ExecutionContext,
+	Injectable,
+	UnauthorizedException,
+} from "@nestjs/common";
+import { ConfigService } from "@nestjs/config";
+import { getIronSession } from "iron-session";
+import { CryptoService } from "../../crypto/crypto.service";
+import { getSessionOptions, SessionData } from "../session.config";
+
+@Injectable()
+export class AuthGuard implements CanActivate {
+	constructor(
+		private readonly cryptoService: CryptoService,
+		private readonly configService: ConfigService,
+	) {}
+
+	async canActivate(context: ExecutionContext): Promise<boolean> {
+		const request = context.switchToHttp().getRequest();
+		const response = context.switchToHttp().getResponse();
+
+		const session = await getIronSession<SessionData>(
+			request,
+			response,
+			getSessionOptions(this.configService.get("SESSION_PASSWORD") as string),
+		);
+
+		const token = session.accessToken;
+
+		if (!token) {
+			throw new UnauthorizedException();
+		}
+
+		try {
+			const payload = await this.cryptoService.verifyJwt(token);
+			request.user = payload;
+		} catch {
+			throw new UnauthorizedException();
+		}
+
+		return true;
+	}
+}