feat: Make validate-frontmatter pip installable

- Created pre_commit_hooks Python package structure
- Added validate-frontmatter console script entry point
- Updated setup.py with entry_points configuration
- Updated pyproject.toml with [project.scripts] section
- Changed .pre-commit-hooks.yaml to use 'validate-frontmatter' command with language: python
- Added pyyaml>=5.0 dependency
- Created MANIFEST.in for proper package distribution
- Added Python build artifacts to .gitignore

The validate-frontmatter hook is now pip installable:
  pip install arustydev-pre-commit-hooks

Usage:
  validate-frontmatter --help
  validate-frontmatter file1.md file2.md
  validate-frontmatter --config custom.json --cache /tmp/cache.json

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: aRustyDev

.gitignore

@@ -0,0 +1,11 @@
+
+# Python build artifacts
+__pycache__/
+*.py[cod]
+*.class
+*.egg-info/
+dist/
+build/
+.eggs/
+.venv/
+venv/

.pre-commit-hooks.yaml

@@ -315,8 +315,9 @@
 - id: validate-frontmatter
   name: Validate Markdown Frontmatter
   description: Validate frontmatter UUIDs and cross-references in markdown files
-  entry: python3 .ai/scripts/validate-frontmatter.py
-  language: system
+  entry: validate-frontmatter
+  language: python
   files: \.md$
   exclude: ^(README\.md|CHANGELOG\.md|\.github/.*\.md|\.ai/templates/.*|\.ai/artifacts/.*|docs/prompts/.*|docs/project-knowledge/user/.*)$
   pass_filenames: true
+  additional_dependencies: []

MANIFEST.in

@@ -0,0 +1,6 @@
+include VERSION
+include README.md
+include LICENSE
+include .pre-commit-hooks.yaml
+recursive-include pre_commit_hooks *.py
+recursive-include hooks *.sh *.nix

pre_commit_hooks/__init__.py

@@ -0,0 +1,3 @@
+"""aRustyDev's pre-commit hooks collection."""
+
+__version__ = "0.2.1"