Add lightweight C# Result pipeline sample

[balajibashyam]

Summary

Adds a minimal .NET 10 companion sample for the C# 12 Functional Patterns: Result Type, Error Handling & Composable Pipeline Testing tutorial.

What's included

• New sample: csharp-language/modern-patterns-result-pipeline/ — 14 files

  • Educational Result<T> hierarchy with Success/Failure cases
  • Public and diagnostic error projections (ToPublic/ToDiagnostic)
  • Map, Bind, Match, and BindAsync composition
  • Restricted comma-delimited parser with exact header, quote rejection, and malformed-row aggregation
  • Invariant-culture collect-all validation
  • Pure name-normalization transformation
  • Deterministic in-memory persistence with configurable rejection
  • Short-circuit behavior (parse/validation failures skip persistence)
  • Caller cancellation propagation without writes
  • C# 12.0 lock with explicit fallback arms in all switch expressions
  • Deterministic console output (five lines)
  • 10 xUnit v3 tests

• Root README: New sample row in the table + updated repository structure

• GitHub Actions: New test-result-pipeline job in the shared workflow; path filters updated

Deliberately omitted (stays in the full tutorial)

Third-party Result packages, FluentAssertions, structured logging, databases, ASP.NET Core, full CSV, partial success, retries, exception swallowing

Versions

• .NET SDK: 10.0.302
• Application NuGet dependencies: none
• Microsoft.NET.Test.Sdk: 18.8.1
• xunit.v3: 3.2.2
• xunit.runner.visualstudio: 3.1.5

Validation

• dotnet restore — passed
• dotnet build --configuration Release — passed (0 errors, 0 warnings)
• dotnet test --configuration Release — passed (10/10)
• Security scan — clean

Commits

1. Add lightweight C# Result pipeline sample
2. Add Result pipeline sample to repository README
3. Test Result pipeline sample in GitHub Actions