Build and publish cx-core .deb package to apt repository

[mikejmorgan-ai]

Summary

Create CI workflow to build .deb package from cx-cli Python source and publish to apt repository at apt.cxlinux.com.

Requirements

• GitHub Actions workflow triggered on release tags
• Build .deb using debhelper/dh-python
• Sign package with GPG key (secrets configured in apt-repo)
• Upload to apt repo pool/main/c/cx/
• Update Packages index

Acceptance Criteria

• apt update && apt install cx-core works on Ubuntu 24.04
• Package installs /usr/bin/cx binary
• Dependencies (python3, firejail) auto-installed
• GPG signature valid

References

• Debian packaging structure exists in packages/cx-core/debian/
• GPG secrets already configured: GPG_PRIVATE_KEY, GPG_KEY_ID

[nailoo]

@mikejmorgan-ai @Anshgrover23 May i work on it,