Add pre-commit (ruff format, ruff check, pip compile) and related workflows

[jpmckinney]

ruff format

• Run ruff format
• Create .git-blame-ignore-revs for the ruff format commit
• Add ruff-format to .pre-commit-config.yaml

ruff check

• Configure ruff check (below) and resolve TODO
• Run ruff check --fix and ruff check --fix --unsafe-fixes
• Work through ruff check --statistics or add to the TODO issue
• Add - id: ruff-check to .pre-commit-config.yaml once ruff check succeeds

uv pip compile

• Switch to requirements.in + requirements.txt
• Configure pre-commit (can do once Configure ruff and fix lints #74 and build: Use uv pip compile requirements.in -o requirements.txt to generate lockfile #73 are merged)

ci:
  autoupdate_schedule: quarterly
  skip: [pip-compile]
# ...
  - repo: https://github.com/astral-sh/uv-pre-commit
    rev: 0.7.19
    hooks:
      - id: pip-compile
        name: pip-compile requirements.in
        args: [requirements.in, -o, requirements.txt]

Miscellaneous

• Create layer/__init__.py to "fix: Add layer/__init__.py to explicitly mark the directory as a Python package"
• Add automerge.yml workflow ci: Configure Dependabot and add auto-merge workflow #72