feat: Implement package management D-Bus methods with client registration

- Add InstallPackages and RemovePackages methods to Sysroot interface
- Implement automatic client registration for D-Bus method calls
- Add client authorization with root/sudo group validation
- Confirm transaction management system working with UUID tracking
- Test all methods successfully with proper D-Bus type handling
- Update CHANGELOG.md with package management milestone
- Update TODO.md to reflect completed daemon integration

The apt-ostree daemon now has a complete package management interface
with working D-Bus methods, client management, and transaction tracking.
Ready for integration with apt-layer.sh for actual package operations.

TODO.md

@@ -40,8 +40,12 @@
 - ✅ D-Bus type compatibility resolved (flattened status dictionary)
 - ✅ Production security policy confirmed (root-only access)
 - ✅ GetStatus method tested and returning valid responses
-- 🎯 Next: Implement additional D-Bus methods (InstallPackages, RemovePackages, etc.)
-- 🎯 Next: Integrate with apt-layer.sh client for full daemon orchestration
+- ✅ InstallPackages and RemovePackages methods implemented and tested
+- ✅ Client management and authorization working correctly
+- ✅ Transaction management system operational
+- 🎯 Next: Implement actual apt-layer.sh integration in D-Bus methods
+- 🎯 Next: Add more D-Bus methods (Deploy, Upgrade, Rollback, etc.)
+- 🎯 Next: Create systemd service files for production deployment
 
 ## Next Phase 🎯