Add lightweight UTF-8 pipelines sample

[balajibashyam]

Summary

Adds a minimal .NET 10 companion sample for the High-Performance C#: Span, Memory, SIMD & Pipelines tutorial.

What's included

• New sample: csharp-language/high-performance-memory-management/ — 13 files

  • PipeReader-based UTF-8 log ingestor with newline framing
  • Single-segment zero-copy parse path
  • Multi-segment bounded MemoryPool copy path
  • Utf8Parser exact-consumption numeric parsing
  • UTF-8 validation via Rune.DecodeFromUtf8
  • CRLF, LF, and final unterminated line support
  • Caller stream ownership and cancellation propagation
  • Bounded oversized-record discard with recovery after newline
  • Deterministic console output with valid/invalid line counts
  • 8 xUnit v3 tests covering parse, decode, and ingest paths

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

• GitHub Actions: New test-high-performance-pipelines job in the shared workflow; path filters updated for push and pull_request

Deliberately omitted (stays in the full tutorial)

stackalloc, unsafe code, MemoryMarshal, SIMD, hardware intrinsics, BenchmarkDotNet, ASP.NET Core, NDJSON, full CSV quoting, performance claims

Versions

• .NET SDK: 10.0.302
• System.IO.Pipelines: provided by the .NET 10 shared framework
• 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 (8/8)
• Security scan — clean

Commits

1. Add lightweight UTF-8 pipelines sample
2. Add pipelines ingestion sample to repository README
3. Test pipelines ingestion sample in GitHub Actions
4. Bound pipeline input and remove pruned package