fix(security): harden auth, upload, and API configuration

- Lock public registration to first-user bootstrap (403 afterwards)
- Require JwtAuthGuard on upload + whitelist png/jpg/webp/gif (SVG/XSS blocked)
- Add global throttling (login/register 5/min, upload 10/min)
- Add helmet security headers; serve uploads with nosniff
- Replace permissive CORS (origin:true+credentials) with CORS_ORIGINS whitelist
- Disable Swagger outside development; sanitize 500 error responses
- Enforce 32+ char JWT_SECRET; make token expiry configurable (TOKEN_EXPIRES_IN)
- Re-check user in DB on every JWT validation (revocation on user delete)
- Dummy bcrypt compare to prevent login user-enumeration via timing
- Map malformed BigInt inputs to 400 instead of 500
- Widen .gitignore to .env* and add apps/api/.env.example
- Disable Nuxt devtools and sourcemaps

apps/api/src/app.module.ts

@@ -1,5 +1,7 @@
 import { Module } from '@nestjs/common';
 import { ConfigModule } from '@nestjs/config';
+import { APP_GUARD } from '@nestjs/core';
+import { ThrottlerGuard, ThrottlerModule } from '@nestjs/throttler';
 import { PrismaModule } from './prisma/prisma.module';
 import { AuthModule } from './auth/auth.module';
 import { CountriesModule } from './countries/countries.module';
@@ -18,6 +20,14 @@ import { UploadModule } from './upload/upload.module';
     ConfigModule.forRoot({
       isGlobal: true,
     }),
+    // Global rate limiting: 120 req/min per IP. Stricter limits are set
+    // per-endpoint with @Throttle (auth, upload).
+    ThrottlerModule.forRoot([
+      {
+        ttl: 60_000,
+        limit: Number(process.env.THROTTLE_LIMIT ?? 120),
+      },
+    ]),
     PrismaModule,
     AuthModule,
     CountriesModule,
@@ -31,5 +41,11 @@ import { UploadModule } from './upload/upload.module';
     PublicModule,
     UploadModule,
   ],
+  providers: [
+    {
+      provide: APP_GUARD,
+      useClass: ThrottlerGuard,
+    },
+  ],
 })
-export class AppModule {}
+export class AppModule {}