feat(security): add per-endpoint API rate limiting with Redis sliding window

Implement @EndpointRateLimit() decorator and EndpointRateLimitGuard for
granular per-endpoint rate limiting using a Redis sorted-set sliding window.
This prevents brute force attacks on auth endpoints, replay attacks on
payment callbacks, and scraping on search endpoints.

Applied rate limits:
- /auth/login: 5 req/min per IP
- /auth/register: 3 req/min per IP
- /listings POST: 10 req/min per user
- /search: 30 req/min per user
- /payments/callback/*: 100 req/min per IP

Features:
- True sliding window (sorted set) for accurate rate measurement
- Configurable key strategy (IP or authenticated user)
- Admin bypass support (enabled by default)
- Fail-open on Redis errors
- Proper 429 response with Retry-After header
- Rate limit headers (X-RateLimit-Limit/Remaining/Reset)
- 22 unit tests covering all scenarios

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/api/src/modules/auth/presentation/controllers/auth.controller.ts

@@ -12,7 +12,7 @@ import { type CommandBus, type QueryBus } from '@nestjs/cqrs';
 import { ApiTags, ApiOperation, ApiResponse, ApiBearerAuth, ApiBody } from '@nestjs/swagger';
 import { Throttle } from '@nestjs/throttler';
 import { type Request, type Response } from 'express';
-import { UnauthorizedException } from '@modules/shared';
+import { EndpointRateLimit, EndpointRateLimitGuard, UnauthorizedException } from '@modules/shared';
 import { LoginUserCommand } from '../../application/commands/login-user/login-user.command';
 import { RefreshTokenCommand } from '../../application/commands/refresh-token/refresh-token.command';
 import { RegisterUserCommand } from '../../application/commands/register-user/register-user.command';
@@ -79,6 +79,8 @@ export class AuthController {
   ) {}
 
   @Throttle({ default: { ttl: 3_600_000, limit: AUTH_RATE_LIMIT }, auth: { ttl: 3_600_000, limit: AUTH_RATE_LIMIT } })
+  @EndpointRateLimit({ limit: IS_TEST ? 10_000 : 3, windowSeconds: 60, keyStrategy: 'ip' })
+  @UseGuards(EndpointRateLimitGuard)
   @Post('register')
   @ApiOperation({ summary: 'Register a new user' })
   @ApiResponse({ status: 201, description: 'User registered, auth cookies set' })
@@ -100,7 +102,8 @@ export class AuthController {
   }
 
   @Throttle({ default: { ttl: 3_600_000, limit: AUTH_RATE_LIMIT }, auth: { ttl: 3_600_000, limit: AUTH_RATE_LIMIT } })
-  @UseGuards(LocalAuthGuard)
+  @EndpointRateLimit({ limit: IS_TEST ? 10_000 : 5, windowSeconds: 60, keyStrategy: 'ip' })
+  @UseGuards(EndpointRateLimitGuard, LocalAuthGuard)
   @Post('login')
   @ApiOperation({ summary: 'Login with phone and password' })
   @ApiBody({ type: LoginDto })