test(benchmarks): add C#/ASP.NET and TypeScript tasks

Six tasks with hidden checks: ASP.NET validation and 404 handling, C#
cancellation, and TypeScript overlap, deep merge, and debounce fixes, checked
with dotnet run and node --test.

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

scripts/benchmarks/tasks/18-ts-deep-merge/hidden/check.test.ts

@@ -0,0 +1,17 @@
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import { mergeConfig } from '../src/config.ts';
+
+test('nested objects merge deeply', () => {
+  const base = { server: { host: 'a', port: 1, tls: { on: true } }, tags: ['x'] };
+  const override = { server: { port: 2, tls: { cert: 'c' } }, tags: ['y', 'z'] };
+  assert.deepEqual(mergeConfig(base, override), { server: { host: 'a', port: 2, tls: { on: true, cert: 'c' } }, tags: ['y', 'z'] });
+});
+
+test('inputs are not mutated', () => {
+  const base = { a: { b: 1 } };
+  const override = { a: { c: 2 } };
+  mergeConfig(base, override);
+  assert.deepEqual(base, { a: { b: 1 } });
+  assert.deepEqual(override, { a: { c: 2 } });
+});