Summary

This PR expands benchmark coverage for ModularityKit.Mutator by adding dedicated diagnostics and concurrency benchmark suites, then updates the CI signing workflow with optional signed package verification.

Highlights

Diagnostics benchmarks

• Add dedicated diagnostics benchmarks under Benchmarks/Diagnostics.
• Measure baseline execution, audit/history overhead, and combined diagnostics overhead.
• Add interceptor overhead benchmarks for passive and logging-style interception.
• Keep diagnostics benchmark mutations, state, stores, and interceptors scoped to the benchmark project.

Concurrency benchmarks

• Add dedicated concurrency benchmarks under Benchmarks/Concurrency.
• Measure parallel execution across distinct runtime state identifiers.
• Measure state level gate contention in the core mutation runtime.
• Measure concurrent batch scheduling under limited runtime availability.
• Add support helpers for repeatable concurrency benchmark scenarios.

Package signing workflow

• Add NUGET_SIGN_SKIP_VERIFICATION support.
• Expose signature_verification_enabled from signing workflow steps.
• Gate signed package verification separately from package signing.
• Allow CI to keep signing enabled while disabling verification when needed.

Why

Issue #58 asks for benchmark visibility into diagnostics overhead across audit, history, and interception paths.

The new concurrency suite adds runtime-level performance coverage for parallel execution, gate contention, and batch scheduling scenarios.

The signing workflow update makes package publishing more flexible by separating signing from signature verification.

Checks

• dotnet build Benchmarks/ModularityKit.Mutator.Benchmarks.csproj -c Release
• sample local BenchmarkDotNet runs for diagnostics and concurrency scenarios

Closes

• Closes [Benchmark]: Measure interception and diagnostics overhead #58
• Closes [Benchmark]: Measure concurrency and gate contention #59