Document benchmark methodology and hardware baseline #857

Description

Explain how gas and storage benches are run, the baseline hardware assumed, and the tolerance CI enforces. Provides context for external contributors reproducing results.

Requirements and context

• Must be secure, tested, and documented
• Should be efficient and easy to review
• Relevant code: docs/benchmarks/methodology.md
• Cross-reference each bench file

Suggested execution

• Fork the repo and create a branch
• git checkout -b docs/bench-methodology
• Implement changes
  • Describe env.cost_estimate usage
  • List baseline hardware CI runs on
  • Explain tolerance and regression policy
• Validate security and correctness assumptions

Test and commit

• Run tests
  • cargo test --all
• Cover edge cases
  • Hardware upgrade re-baseline, noisy runs, and known-flaky benches
• Include test output and security notes

Example commit message

docs: benchmark methodology and baselines

Guidelines

• Minimum 95 percent test coverage
• Clear documentation
• Timeframe: 96 hours