Package pkgmgr with multi-format manifests

- Add pyproject.toml and setuptools config for pkgmgr packaging
- Add Nix flake (devShell + pkgmgr package output)
- Add Arch PKGBUILD for system packaging
- Introduce pkgmgr.yml manifest for repo-level dependencies
- Refactor CLI into pkgmgr/cli.py and make main.py a thin entrypoint
- Extend install_repos to handle pkgmgr.yml, PKGBUILD, flake.nix, Ansible and Python manifests
- Enhance status/update to show Nix/yay system status and upgrades
- Improve .gitignore and document requirements.yml

Created with AI (ChatGPT) – see conversation: https://chatgpt.com/share/6932f2ca-f560-800f-8bb0-52cb82f27e88

PKGBUILD

@@ -0,0 +1,39 @@
+# Maintainer: Kevin Veen-Birkenbach <info@veen.world>
+
+pkgname=package-manager
+pkgver=0.1.0
+pkgrel=1
+pkgdesc="A configurable Python tool to manage multiple repositories via Bash and automate common Git operations."
+arch=('any')
+url="https://github.com/kevinveenbirkenbach/package-manager"
+license=('MIT')
+
+depends=(
+  'python'
+  'python-yaml'
+  'git'
+  'bash'
+)
+
+makedepends=(
+  'python-build'
+  'python-installer'
+  'python-wheel'
+  'python-setuptools'
+)
+
+source=("$pkgname-$pkgver.tar.gz::$url/archive/refs/tags/v$pkgver.tar.gz")
+sha256sums=('SKIP')
+
+build() {
+  cd "$srcdir/$pkgname-$pkgver"
+  python -m build --wheel --no-isolation
+}
+
+package() {
+  cd "$srcdir/$pkgname-$pkgver"
+  python -m installer --destdir="$pkgdir" dist/*.whl
+
+  # Optional: add pkgmgr executable symlink
+  install -Dm755 main.py "$pkgdir/usr/bin/pkgmgr"
+}