ci: add GHCR container publish pipeline with semantic tags

Introduce a dedicated publish-containers workflow triggered after stable releases.
Unify container build and publish logic via scripts, add buildx-based multi-tag publishing,
default base image resolution, and Arch alias tags for latest/version/stable.

https://chatgpt.com/share/693c836b-0b00-800f-9536-9e273abd0fb5

scripts/build/publish.sh

@@ -0,0 +1,55 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# Publish all distro images (full + virgin) to a registry via image.sh --publish
+#
+# Required env:
+#   OWNER      (e.g. GITHUB_REPOSITORY_OWNER)
+#   VERSION    (e.g. 1.2.3)
+#
+# Optional env:
+#   REGISTRY   (default: ghcr.io)
+#   IS_STABLE  (default: false)
+#   DISTROS    (default: "arch debian ubuntu fedora centos")
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+
+REGISTRY="${REGISTRY:-ghcr.io}"
+IS_STABLE="${IS_STABLE:-false}"
+DISTROS="${DISTROS:-arch debian ubuntu fedora centos}"
+
+: "${OWNER:?Environment variable OWNER must be set (e.g. github.repository_owner)}"
+: "${VERSION:?Environment variable VERSION must be set (e.g. 1.2.3)}"
+
+echo "[publish] REGISTRY=${REGISTRY}"
+echo "[publish] OWNER=${OWNER}"
+echo "[publish] VERSION=${VERSION}"
+echo "[publish] IS_STABLE=${IS_STABLE}"
+echo "[publish] DISTROS=${DISTROS}"
+
+for d in ${DISTROS}; do
+  echo
+  echo "============================================================"
+  echo "[publish] distro=${d}"
+  echo "============================================================"
+
+  # virgin
+  distro="${d}" bash "${SCRIPT_DIR}/image.sh" \
+    --publish \
+    --registry "${REGISTRY}" \
+    --owner "${OWNER}" \
+    --version "${VERSION}" \
+    --stable "${IS_STABLE}" \
+    --target virgin
+
+  # full (default target)
+  distro="${d}" bash "${SCRIPT_DIR}/image.sh" \
+    --publish \
+    --registry "${REGISTRY}" \
+    --owner "${OWNER}" \
+    --version "${VERSION}" \
+    --stable "${IS_STABLE}"
+done
+
+echo
+echo "[publish] Done."