feat: Automated PyPI publishing on release tags

[dbhurley]

Summary

Adds automated publishing to PyPI when version tags are pushed.

Workflow

1. Trigger: Push of tags matching v*.*.*
2. Test: Runs full test suite across Python 3.9-3.12
3. Build: Creates and validates package with twine check
4. Publish: Pushes to PyPI using trusted publishing

Required Secrets

Configure this secret in the repository settings:

Secret	Source	Description
PYPI_API_TOKEN	PyPI API tokens	API token with upload permissions for meshguard

Alternative: Trusted Publishing (OIDC)

For enhanced security, configure PyPI Trusted Publishing which eliminates the need for storing API tokens.

Usage

To publish a new version:

# Update version in pyproject.toml
git tag v0.2.0
git push origin v0.2.0

Closes

Issue #7