feat(middleware): add crawler detection middleware for suspicious requests

Introduce `CrawlerDetectionMiddleware` to identify and log potential crawlers or bots accessing suspicious paths or using bot-like user agents. Middleware applied globally to all routes in `AppModule`.

backend/src/app.module.ts

@@ -1,5 +1,5 @@
 import { CacheModule } from "@nestjs/cache-manager";
-import { Module } from "@nestjs/common";
+import { MiddlewareConsumer, Module, NestModule } from "@nestjs/common";
 import { ConfigModule, ConfigService } from "@nestjs/config";
 import { ScheduleModule } from "@nestjs/schedule";
 import { ThrottlerModule } from "@nestjs/throttler";
@@ -10,6 +10,7 @@ import { AppService } from "./app.service";
 import { AuthModule } from "./auth/auth.module";
 import { CategoriesModule } from "./categories/categories.module";
 import { CommonModule } from "./common/common.module";
+import { CrawlerDetectionMiddleware } from "./common/middlewares/crawler-detection.middleware";
 import { validateEnv } from "./config/env.schema";
 import { ContentsModule } from "./contents/contents.module";
 import { CryptoModule } from "./crypto/crypto.module";
@@ -71,4 +72,8 @@ import { UsersModule } from "./users/users.module";
 	controllers: [AppController, HealthController],
 	providers: [AppService],
 })
-export class AppModule {}
+export class AppModule implements NestModule {
+	configure(consumer: MiddlewareConsumer) {
+		consumer.apply(CrawlerDetectionMiddleware).forRoutes("*");
+	}
+}