Phase 1: Add Linux distribution packages (.deb and .rpm)

[httpdss]

Issue

Phase 1 of Linux distribution packaging as requested.

Description

This PR introduces comprehensive Linux distribution packaging for structkit, enabling easy installation via native package managers on Debian/Ubuntu (.deb) and Fedora/RHEL (.rpm) systems.

Key Changes

Package Structure:

• Created packaging/debian/ and packaging/rpm/ directories with nfpm configurations
• Implemented vendored virtual environment approach at /usr/lib/structkit/venv/
• Added CLI shim script at /usr/bin/structkit that invokes the vendored environment
• Packaged all Python dependencies to avoid conflicts with system packages

Build System:

• New GitHub Actions workflow .github/workflows/build-linux-packages.yaml
• Triggers on release events and manual workflow dispatch
• Builds both amd64 and arm64 packages for each format (4 total artifacts per run)
• Integrates with existing PyPI publish workflow without interference

Documentation:

• Comprehensive packaging/README.md with:
  • Local build instructions
  • Installation instructions for both package formats
  • CI/CD workflow documentation
  • Troubleshooting guidance

Technical Implementation

The packages use a vendored Python environment to handle dependencies that aren't available in distribution repositories:

/usr/lib/structkit/venv/     # Complete Python environment with all dependencies
/usr/bin/structkit           # Wrapper script that invokes vendored structkit
/usr/share/doc/structkit/    # Documentation (README, LICENSE)

This approach ensures:

• No conflicts with system Python packages
• Consistent dependency versions across distributions
• Simple installation without requiring pip or manual venv management

Build Results

Successfully tested local builds:

• ✅ structkit_3.2.1_amd64.deb (46 MB)
• ✅ structkit-3.2.1-1.x86_64.rpm (48 MB)
• ✅ Verified package installation and CLI functionality

Installation

Debian/Ubuntu:

sudo dpkg -i structkit_VERSION_amd64.deb

Fedora/RHEL:

sudo dnf install ./structkit-VERSION-1.x86_64.rpm

Out of Scope (Future Phases)

As specified in requirements, this PR does NOT include:

• Submission to Debian mentors or Fedora review processes
• PPA/COPR repository setup
• Official distribution repository inclusion
• Package signing/verification
• Marketplace/catalog integration

Checklist

• I have read the contributing guidelines
• My code follows the code style of this project
• I have performed a self-review of my own code
• I have added documentation for the new features
• I have tested the build and installation process locally
• The workflow does not interfere with existing PyPI publish workflow

Additional Comments

Workflow Usage:

• Reviewers can test the workflow manually via Actions → build-linux-packages → Run workflow
• Or trigger automatically by creating a release
• Artifacts will be uploaded with 90-day retention for testing

Architecture Support:

• Primary target is amd64 (tested and working)
• arm64 builds included in workflow but may require testing on ARM hardware

Package Size:

• Packages are ~46-48 MB due to vendored Python dependencies
• This is expected and necessary to ensure compatibility across distributions