feat(pkgbuilds): add anaconda dependencies packaging

Add PKGBUILD files for four Anaconda installer dependencies:
- pykickstart: Kickstart language parser (>= 3.73)
- python-blivet: Storage management abstraction layer
- python-productmd: OS product metadata parsers
- python-requests-file: file:// URL transport adapter for requests

These packages are required by rhinstaller but absent from Arch repos and AUR.
All use manual module installation to avoid unnecessary build dependencies.

Also fix .gitignore by removing pkgbuilds/ exclusion to allow tracking these new packages.

pkgbuilds/python-productmd/PKGBUILD

@@ -0,0 +1,28 @@
+# Maintainer: FWS
+# Dépendance de l'installateur Anaconda (rhinstaller) — parseur des métadonnées
+# de produit/compose (.treeinfo, .discinfo). Absent des dépôts Arch et de l'AUR.
+# Pur Python, stdlib uniquement (aucun install_requires) : install manuel de
+# l'arborescence du module.
+pkgname=python-productmd
+pkgver=1.50
+pkgrel=1
+pkgdesc="Library providing parsers for metadata related to OS products (dépendance Anaconda)"
+arch=('any')
+url="https://github.com/release-engineering/productmd"
+license=('LGPL-2.1-or-later')
+depends=('python')
+_tag="v$pkgver"
+source=("$pkgname-$pkgver.tar.gz::https://github.com/release-engineering/productmd/archive/refs/tags/$_tag.tar.gz")
+sha256sums=('2b780882e529cf5a26a9a7d55a269a360886bf2b50357fcca0934a9fa3437d27')
+_srcdir="productmd-$pkgver"
+
+package() {
+  cd "$srcdir/$_srcdir"
+  local sitedir
+  sitedir=$(python -c 'import site; print(site.getsitepackages()[0])')
+  install -d "$pkgdir$sitedir"
+  cp -a productmd "$pkgdir$sitedir/productmd"
+  # -d : grave le chemin d'exécution réel dans les .pyc (pas le $pkgdir de build).
+  python -m compileall -q -d "$sitedir/productmd" "$pkgdir$sitedir/productmd" || true
+  install -Dm644 LICENSE "$pkgdir/usr/share/licenses/$pkgname/LICENSE"
+}