Harden scaffold (reviewer followups)

- main.ts awaits DatabaseInitService.init() before app.listen(), ensuring
  migrations + seed run before the HTTP server accepts traffic.
- AppModule now uses NestModule with consumer.apply() no longer needed for
  CSRF (registered globally via app.use after body parsers in main.ts).
- JwtAuthGuard extended from AuthGuard('jwt') so protected endpoints
  actually validate the bearer token.
- Admin controller now uses Zod-validated DTOs for body/path/query:
  createUser, updateUserRole, userIdParam, listUsersQuery; with @Public
  / @Roles decorators and AdminGuard applied.
- Multer upload module + controller (POST /api/v1/uploads/category-icon
  and /challenge-file) with safe-filename strategy, configured
  UPLOAD_SIZE_LIMIT, admin-only via AdminGuard, served via /uploads
  static handler.
- ThemeLoaderService now requires all 10 canonical theme ids at startup,
  backfilling missing themes from built-ins with a warning; validates the
  configured themeKey setting and falls back to 'classic' if invalid;
  gracefully tolerates missing setting table during early boot.
- Test suite expanded to 76 tests / 17 suites; new specs:
  admin-validation, uploads, theme-required, database-init.

tests/backend/auth-refresh.spec.ts

@@ -6,22 +6,31 @@ import { Test } from '@nestjs/testing';
 import { INestApplication, ValidationPipe } from '@nestjs/common';
 import { HttpAdapterHost } from '@nestjs/core';
 import cookieParser from 'cookie-parser';
+import * as express from 'express';
 import request from 'supertest';
 import { CookieAccessInfo } from 'cookiejar';
 import { AppModule } from '../../backend/src/app.module';
 import { GlobalExceptionFilter } from '../../backend/src/common/filters/global-exception.filter';
+import { CsrfMiddleware } from '../../backend/src/common/middleware/csrf.middleware';
+import { ConfigService } from '@nestjs/config';
+import { initDb } from './db-helper';
+import { DatabaseInitService } from '../../backend/src/database/database-init.service';
 
 describe('Auth refresh rotation', () => {
   let app: INestApplication;
 
-  beforeAll(async () => {
+beforeAll(async () => {
     const moduleRef = await Test.createTestingModule({ imports: [AppModule] }).compile();
     app = moduleRef.createNestApplication();
     app.use(cookieParser());
+    app.use(express.json({ limit: '1mb' }));
+    const csrfMw = new CsrfMiddleware(app.get(ConfigService));
+    app.use((req: any, res: any, next: any) => csrfMw.use(req, res, next));
     app.useGlobalPipes(new ValidationPipe({ whitelist: true, forbidNonWhitelisted: false, transform: true }));
     const httpAdapterHost = app.get(HttpAdapterHost);
     app.useGlobalFilters(new GlobalExceptionFilter(httpAdapterHost));
     await app.init();
+    await initDb(app);
 
     const server = app.getHttpServer();
     await request(server).post('/api/v1/auth/register-first-admin')