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/package.json

@@ -34,6 +34,7 @@
     "@nestjs/platform-express": "^10.3.0",
     "@nestjs/schedule": "^4.0.0",
     "@nestjs/swagger": "^7.1.17",
+    "@nestjs/throttler": "^6.5.0",
     "@prisma/client": "^5.8.0",
     "@types/multer": "^2.2.0",
     "axios": "^1.6.5",
@@ -41,6 +42,7 @@
     "class-transformer": "^0.5.1",
     "class-validator": "^0.14.0",
     "express": "^4.21.0",
+    "helmet": "^8.3.0",
     "multer": "^2.2.0",
     "passport": "^0.7.0",
     "passport-jwt": "^4.0.1",