test(benchmarks): tag tasks as small change, larger implementation, or search

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

scripts/benchmarks/tasks/14-aspnet-order-validation/task.json

@@ -1,4 +1,5 @@
 {
+  "category": "larger implementation",
   "prompt": "POST /orders accepts orders with a zero or negative quantity and orders with an empty SKU. Reject those with HTTP 400 and a validation problem response; valid orders must still return 201.",
   "check": [
     "dotnet",