chore: add ruff formatter, .gitignore, and uv convention (#40)

* chore: add ruff formatter, .gitignore, and uv convention

- Add ruff as dev dependency with basic config
- Add PostToolUse hook to auto-run ruff on .py edits
- Create .gitignore to exclude __pycache__ and settings.local.json
- Document uv run convention in CLAUDE.md
- Add CLAUDE.md, .claude/settings.json, and skills
- Apply ruff formatting to existing Python files

* fix: address CR feedback on hooks and uv run convention

- Fix hooks to read file_path from stdin JSON via jq instead of
  nonexistent $CLAUDE_FILE env var
- Update CLAUDE.md commands to use uv run python3 consistently
- Update skills to use uv run for python/dedup commands

pyproject.toml

@@ -9,7 +9,11 @@ dependencies = [
 ]
 
 [dependency-groups]
-dev = ["pytest>=8.0"]
+dev = ["pytest>=8.0", "ruff>=0.11"]
+
+[tool.ruff]
+target-version = "py311"
+line-length = 120
 
 [project.scripts]
 dedup = "dedup:main"