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/common/filters/http-exception.filter.ts

@@ -32,9 +32,24 @@ export class HttpExceptionFilter implements ExceptionFilter {
     const request = ctx.getRequest<Request>();
 
     const status =
-      exception instanceof HttpException
-        ? exception.getStatus()
-        : HttpStatus.INTERNAL_SERVER_ERROR;
+      exception instanceof HttpException ? exception.getStatus() : HttpStatus.INTERNAL_SERVER_ERROR;
+
+    // Malformed bigint/number inputs (e.g. `BigInt("abc")`) are client
+    // errors — map them to 400 instead of leaking a 500.
+    if (
+      status === HttpStatus.INTERNAL_SERVER_ERROR &&
+      exception instanceof Error &&
+      /Cannot convert .+ to (a BigInt|number)/i.test(exception.message)
+    ) {
+      response.status(HttpStatus.BAD_REQUEST).json({
+        statusCode: HttpStatus.BAD_REQUEST,
+        message: 'Invalid numeric identifier',
+        error: 'BadRequestError',
+        timestamp: new Date().toISOString(),
+        path: request.url,
+      });
+      return;
+    }
 
     let message: string | string[] = 'Internal server error';
     let error = 'InternalServerError';
@@ -51,11 +66,15 @@ export class HttpExceptionFilter implements ExceptionFilter {
         message = exception.message;
       }
     } else if (exception instanceof Error) {
-      message = exception.message;
-      error = exception.name;
+      // Unexpected errors (Prisma, driver, ...) may contain SQL or
+      // connection details — never send them to the client.
+      this.logger.error(
+        `${request.method} ${request.url} -> ${status} ${exception.message}`,
+        exception.stack,
+      );
     }
 
-    if (status >= 500) {
+    if (status >= 500 && exception instanceof HttpException) {
       this.logger.error(
         `${request.method} ${request.url} -> ${status} ${message}`,
         exception instanceof Error ? exception.stack : undefined,