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/auth/auth.controller.ts

@@ -1,5 +1,6 @@
 import { Body, Controller, Headers, Post, Req, Res } from "@nestjs/common";
 import { ConfigService } from "@nestjs/config";
+import { Throttle } from "@nestjs/throttler";
 import type { Request, Response } from "express";
 import { getIronSession } from "iron-session";
 import { AuthService } from "./auth.service";
@@ -16,11 +17,13 @@ export class AuthController {
 	) {}
 
 	@Post("register")
+	@Throttle({ default: { limit: 5, ttl: 60000 } })
 	register(@Body() registerDto: RegisterDto) {
 		return this.authService.register(registerDto);
 	}
 
 	@Post("login")
+	@Throttle({ default: { limit: 5, ttl: 60000 } })
 	async login(
 		@Body() loginDto: LoginDto,
 		@Headers("user-agent") userAgent: string,
@@ -52,6 +55,7 @@ export class AuthController {
 	}
 
 	@Post("verify-2fa")
+	@Throttle({ default: { limit: 5, ttl: 60000 } })
 	async verifyTwoFactor(
 		@Body() verify2faDto: Verify2faDto,
 		@Headers("user-agent") userAgent: string,

backend/src/auth/auth.service.ts

@@ -1,6 +1,7 @@
 import {
 	BadRequestException,
 	Injectable,
+	Logger,
 	UnauthorizedException,
 } from "@nestjs/common";
 import { ConfigService } from "@nestjs/config";
@@ -14,6 +15,8 @@ import { RegisterDto } from "./dto/register.dto";
 
 @Injectable()
 export class AuthService {
+	private readonly logger = new Logger(AuthService.name);
+
 	constructor(
 		private readonly usersService: UsersService,
 		private readonly cryptoService: CryptoService,
@@ -22,6 +25,7 @@ export class AuthService {
 	) {}
 
 	async generateTwoFactorSecret(userId: string) {
+		this.logger.log(`Generating 2FA secret for user ${userId}`);
 		const user = await this.usersService.findOne(userId);
 		if (!user) throw new UnauthorizedException();
 
@@ -42,6 +46,7 @@ export class AuthService {
 	}
 
 	async enableTwoFactor(userId: string, token: string) {
+		this.logger.log(`Enabling 2FA for user ${userId}`);
 		const secret = await this.usersService.getTwoFactorSecret(userId);
 		if (!secret) {
 			throw new BadRequestException("2FA not initiated");
@@ -57,6 +62,7 @@ export class AuthService {
 	}
 
 	async disableTwoFactor(userId: string, token: string) {
+		this.logger.log(`Disabling 2FA for user ${userId}`);
 		const secret = await this.usersService.getTwoFactorSecret(userId);
 		if (!secret) {
 			throw new BadRequestException("2FA not enabled");
@@ -72,6 +78,7 @@ export class AuthService {
 	}
 
 	async register(dto: RegisterDto) {
+		this.logger.log(`Registering new user: ${dto.username}`);
 		const { username, email, password } = dto;
 
 		const passwordHash = await this.cryptoService.hashPassword(password);
@@ -91,6 +98,7 @@ export class AuthService {
 	}
 
 	async login(dto: LoginDto, userAgent?: string, ip?: string) {
+		this.logger.log(`Login attempt for email: ${dto.email}`);
 		const { email, password } = dto;
 
 		const emailHash = await this.cryptoService.hashEmail(email);
@@ -141,6 +149,7 @@ export class AuthService {
 		userAgent?: string,
 		ip?: string,
 	) {
+		this.logger.log(`2FA verification attempt for user ${userId}`);
 		const user = await this.usersService.findOneWithPrivateData(userId);
 		if (!user || !user.isTwoFactorEnabled) {
 			throw new UnauthorizedException();