feat: create autonomous Nivora package repository

Maintain a validated cross-distribution package catalog.
Automate upstream updates, isolated builds, diagnostics, and direct publication.
Build the official GitHub Desktop sources for Linux with working OAuth.

codex/.stapler/update-check

@@ -0,0 +1,6 @@
+#!/bin/bash
+set -euo pipefail
+
+package_dir="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+repo_root="$(cd "${package_dir}/.." && pwd)"
+exec "${repo_root}/tools/package_updates.sh" check "$(basename "$package_dir")"