feat: add debian packaging, CI/CD and update script

- Add debian/ packaging for .deb generation
- Add .forgejo/workflows/build.yml for CI/CD (runner label: docker)
- Add scripts/fullupdater and scripts/fullupdater-update
- Remove obsolete install.sh
- Update .gitignore for debian build artifacts

debian/control

@@ -0,0 +1,15 @@
+Source: full-updater
+Section: admin
+Priority: optional
+Maintainer: Enzo <admin@geronzi.fr>
+Build-Depends: debhelper-compat (= 13), dh-python, python3-all, python3-venv
+Standards-Version: 4.6.0
+
+Package: full-updater
+Architecture: all
+Depends: ${python3:Depends}, python3-textual, python3-pyperclip, python3-venv, git, pct
+Description: TUI for APT/CVE updates on Proxmox host and LXC
+ Full Updater is a terminal user interface (TUI) that visualizes
+ available APT updates and CVEs for the Proxmox host and all LXC
+ containers. It supports keyboard and mouse controls, real-time
+ scanning, caching, and one-click upgrades via pct exec.