ci: add cut-release workflow, remove duplicate CI, pre-commit hooks, docs updates

[Dongbumlee]

Summary

Adds a one-click Cut Release workflow, removes duplicate CI runs, adds pre-commit hooks, and updates release documentation.

Changes

CI/CD Workflows

• New: cut-release.yml - Manual dispatch workflow (Actions tab button) to create release branches from develop
• Remove duplicate CI on release branches - ci.yml no longer triggers on release/** pushes
• Add lint to reusable build - _build.yml now includes ruff check before tests
• Remove macOS from test matrix - Avoids queue delays
• Fix ruff E402 lint error - Moved mid-file import in test_foundry_backend.py

Developer Experience

• Add pre-commit hooks - ruff lint and ruff-format on every commit
• Add pre-commit to dev dependencies

Documentation

• release-process.md - Added cut-release docs, updated steps, architecture diagram, checklist
• ci-github-actions.md - Added Internal CI/CD Workflows section

CI Pipeline

Trigger	Workflow	What runs
Push to develop	ci.yml	lint + test + coverage
PR to main/develop	ci.yml	lint + test + coverage
Push to release/**	staging.yml	lint + test + build + TestPyPI + verify
Push v* tag	release.yml	TestPyPI + PyPI + GitHub Release
Manual button	cut-release.yml	Create release branch + CHANGELOG + PR