test: run integration tests natively on macOS

[korniltsev-grafanista]

Summary

• add a native process backend so the existing Go integration suite can run Pyroscope and Python workloads directly on macOS
• discover Darwin wheels and run the full suite for Python 3.10-3.14 on both Intel and ARM GitHub runners
• pin and checksum-verify the native Pyroscope test binary while preserving the existing Linux Docker path

Test plan

• Run the full native macOS ARM suite against Python 3.14
• Run go test -race -run '^$' ./...
• Run go vet ./...
• Validate workflow YAML and wheel architecture/tags
• Confirm the complete Intel and ARM matrices in GitHub Actions