Add benchmark evidence reporter and automation

[EricCogen]

Introduce GauntletCI.BenchmarkReporter, a .NET console app that generates benchmark evidence reports (JSON/CSV) from the curated fixture corpus. Add supporting test project for CLI parsing. Integrate a new GitHub Actions workflow to automate report generation and artifact upload. Update README with experimental evidence documentation and usage. No changes to core analysis logic; all additions focus on evidence reporting, automation, and documentation.

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Include benchmark reporter tests in solution

Add tests/GauntletCI.BenchmarkReporter.Tests/GauntletCI.BenchmarkReporter.Tests.csproj to GauntletCI.slnx; otherwise the new parser tests are never executed in CI. I checked .github/workflows/ci.yml and .github/workflows/release.yml, and both run dotnet test GauntletCI.slnx, so omitting this project from the solution means regressions in the new reporter CLI parsing can ship unnoticed.

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[Copilot]

Pull request overview

This PR introduces a new benchmark evidence reporting console app and associated automation to generate and publish JSON/CSV reports derived from the curated benchmark fixture corpus.

Changes:

• Add GauntletCI.BenchmarkReporter console app to evaluate curated fixtures and emit latest.json / latest.csv.
• Add a new test project to validate CLI option parsing for the reporter.
• Add a scheduled/manual GitHub Actions workflow to generate and upload benchmark evidence artifacts; document usage in README.md.

Reviewed changes

Copilot reviewed 8 out of 9 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/GauntletCI.BenchmarkReporter/Program.cs	Implements reporter CLI parsing, fixture evaluation, JSON/CSV output, and report schema records.
src/GauntletCI.BenchmarkReporter/GauntletCI.BenchmarkReporter.csproj	Adds new console app project and InternalsVisibleTo for tests.
tests/GauntletCI.BenchmarkReporter.Tests/ReporterOptionsParseTests.cs	Adds unit tests for reporter option parsing defaults and flags.
tests/GauntletCI.BenchmarkReporter.Tests/GauntletCI.BenchmarkReporter.Tests.csproj	Adds new xUnit test project referencing the reporter project.
.github/workflows/benchmark-evidence.yml	Automates report generation and uploads JSON/CSV artifacts on schedule/dispatch.
docs/benchmarks/latest.json	Adds generated benchmark evidence (JSON) snapshot.
docs/benchmarks/latest.csv	Adds generated benchmark evidence (CSV) snapshot.
README.md	Documents experimental evidence generation, outputs, and workflow automation.
GauntletCI.slnx	Adds the new reporter project to the solution.

Comments suppressed due to low confidence (1)

GauntletCI.slnx:13

• GauntletCI.slnx is used by CI (dotnet test GauntletCI.slnx) but the new tests/GauntletCI.BenchmarkReporter.Tests project isn’t included under the /tests/ folder. As a result, the new CLI parsing tests won’t run in CI or when running solution-based tests locally. Add the new test .csproj to the solution’s /tests/ folder (and consider keeping the folder list complete for new test projects going forward).

<Solution>
  <Folder Name="/src/">
    <Project Path="src/GauntletCI.BenchmarkReporter/GauntletCI.BenchmarkReporter.csproj" />
    <Project Path="src/GauntletCI.Cli/GauntletCI.Cli.csproj" />
    <Project Path="src/GauntletCI.Core/GauntletCI.Core.csproj" />
    <Project Path="src/GauntletCI.PrIntegration.Host/GauntletCI.PrIntegration.Host.csproj" />
    <Project Path="src/GauntletCI.PrIntegration/GauntletCI.PrIntegration.csproj" />
  </Folder>
  <Folder Name="/tests/">
    <Project Path="tests/GauntletCI.Benchmarks/GauntletCI.Benchmarks.csproj" />
    <Project Path="tests/GauntletCI.Cli.Tests/GauntletCI.Cli.Tests.csproj" />
    <Project Path="tests/GauntletCI.Core.Tests/GauntletCI.Core.Tests.csproj" />
  </Folder>

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[Copilot]

The help text defaults don’t match the actual parsing logic:

• --repo-root help says “default: current directory”, but ResolveDefaultRepoRoot() walks up to find a directory that looks like the repo root.
• --fixtures-root help says “default: ../tests/...”, but Parse() defaults to <repoRoot>/tests/GauntletCI.Benchmarks/Fixtures/curated.
  Update HelpText so the documented defaults match the behavior.

[Copilot]

New src/ C# source files in this repo consistently start with the SPDX license header (e.g., src/GauntletCI.Cli/Program.cs). GauntletCI.BenchmarkReporter/Program.cs currently lacks that header, which can create licensing/compliance inconsistencies. Add the standard SPDX + copyright header at the top of this file.

[Copilot]

The workflow builds the reporter in Release (dotnet build ... --no-restore) and then runs it via dotnet run, which will trigger another build unless --no-build is specified. Consider adding --no-build to the dotnet run invocation to avoid redundant compilation and speed up scheduled runs.

Suggested change

	dotnet run --project src/GauntletCI.BenchmarkReporter/GauntletCI.BenchmarkReporter.csproj --configuration Release -- "${args[@]}"
	dotnet run --project src/GauntletCI.BenchmarkReporter/GauntletCI.BenchmarkReporter.csproj --configuration Release --no-build -- "${args[@]}"