feat: add @nestjs/swagger and swagger-ui-express dependencies for API documentation

backend/package.json

@@ -33,6 +33,7 @@
     "@nestjs/passport": "^11.0.5",
     "@nestjs/platform-express": "^11.0.1",
     "@nestjs/platform-socket.io": "^11.1.1",
+    "@nestjs/swagger": "^11.2.0",
     "@nestjs/websockets": "^11.1.1",
     "@node-rs/argon2": "^2.0.2",
     "class-transformer": "^0.5.1",
@@ -48,6 +49,7 @@
     "reflect-metadata": "^0.2.2",
     "rxjs": "^7.8.1",
     "socket.io": "^4.8.1",
+    "swagger-ui-express": "^5.0.1",
     "uuid": "^11.1.0",
     "zod": "^3.24.4",
     "zod-validation-error": "^3.4.1"