feat: add logging and caching enhancements across core services

Integrate `Logger` for consistent logging in services like `reports`, `categories`, `users`, `contents`, and more. Introduce caching capabilities with `CacheInterceptor` and manual cache clearing logic for categories, users, and contents. Add request throttling to critical auth endpoints for enhanced rate limiting.

backend/src/api-keys/api-keys.service.ts

@@ -1,14 +1,17 @@
 import { createHash, randomBytes } from "node:crypto";
-import { Injectable } from "@nestjs/common";
+import { Injectable, Logger } from "@nestjs/common";
 import { and, eq } from "drizzle-orm";
 import { DatabaseService } from "../database/database.service";
 import { apiKeys } from "../database/schemas";
 
 @Injectable()
 export class ApiKeysService {
+	private readonly logger = new Logger(ApiKeysService.name);
+
 	constructor(private readonly databaseService: DatabaseService) {}
 
 	async create(userId: string, name: string, expiresAt?: Date) {
+		this.logger.log(`Creating API key for user ${userId}: ${name}`);
 		const prefix = "mg_live_";
 		const randomPart = randomBytes(24).toString("hex");
 		const key = `${prefix}${randomPart}`;
@@ -46,6 +49,7 @@ export class ApiKeysService {
 	}
 
 	async revoke(userId: string, keyId: string) {
+		this.logger.log(`Revoking API key ${keyId} for user ${userId}`);
 		return await this.databaseService.db
 			.update(apiKeys)
 			.set({ isActive: false, updatedAt: new Date() })