Add omarchycn-keyring package and container build script

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QKxGW1raAWaqeU8WdHsMsp

packages/omarchycn-keyring/PKGBUILD

@@ -0,0 +1,20 @@
+pkgname=omarchycn-keyring
+pkgver=20260824
+pkgrel=1
+pkgdesc="OmarchyCN PGP keyring: package registry and release signing keys"
+arch=(any)
+url="https://git.zacharyzhang.com/ZacharyZhang-NY/omarchycn"
+license=(MIT)
+install=omarchycn-keyring.install
+source=(omarchycn-registry.asc omarchycn-release.asc omarchycn-trusted)
+sha256sums=(SKIP SKIP SKIP)
+
+build() {
+  cat omarchycn-registry.asc omarchycn-release.asc | gpg --dearmor > omarchycn.gpg
+}
+
+package() {
+  install -Dm644 omarchycn.gpg "$pkgdir/usr/share/pacman/keyrings/omarchycn.gpg"
+  install -Dm644 omarchycn-trusted "$pkgdir/usr/share/pacman/keyrings/omarchycn-trusted"
+  install -Dm644 /dev/null "$pkgdir/usr/share/pacman/keyrings/omarchycn-revoked"
+}