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/15-csharp-cancellation/repo/src/Reports/ReportBuilder.cs

@@ -0,0 +1,15 @@
+namespace Reports;
+
+public sealed class ReportBuilder
+{
+    public async Task<string> BuildAsync(IEnumerable<string> sections, CancellationToken cancellationToken = default)
+    {
+        var parts = new List<string>();
+        foreach (var section in sections)
+        {
+            await Task.Delay(100);
+            parts.Add($"## {section}");
+        }
+        return string.Join("\n", parts);
+    }
+}

scripts/benchmarks/tasks/15-csharp-cancellation/repo/src/Reports/Reports.csproj

@@ -0,0 +1,7 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+  </PropertyGroup>
+</Project>