Add a Gitea Actions pipeline that publishes the image as a release

Builds the image on a self-hosted runner and publishes it, with the checksum and
a corresponding-source offer, as a Gitea release.

The schedule is daily but the build is conditional. Proxmox does not ship daily,
so an unconditional daily build would produce roughly 45 GB a month of
near-identical artifacts; instead the job compares the newest pve-manager in the
configured repository against the last published release and stops early when
they match. A manual trigger with `force` rebuilds anyway. Releases are tagged
after the version they contain (`pve-9.2.11`) rather than the date, so the tag
says something useful, and older ones are pruned to keep three.

The logic lives in scripts/ci/ rather than inline in the workflow. Shell inside a
YAML block scalar cannot carry an indented heredoc terminator, and the release
body needs several; scripts also mean the pieces can be run and tested by hand.
A `print-var` target exposes single Makefile variables to them.

Two constraints shaped this:

  * The runner is registered in host mode, so steps run directly on the build
    machine as root. The build needs /dev/kvm, qemu-nbd, FUSE and root, which a
    container would have to be given anyway. The consequence — anything able to
    dispatch a workflow gets root on that machine — is stated in the workflow
    header rather than left implicit.
  * Checkout is a plain git clone. actions/checkout is a JavaScript action and
    the host-mode runner has no Node.js runtime.

The artifact is named maas-image-pve-<version>-amd64.tar.gz, not
proxmox-ve-*.tar.gz, and the release body says the build is unofficial and
unaffiliated. Proxmox permits redistribution under the AGPLv3 but asks that the
trademark not be used in product names.

SOURCES.md is generated per release: the image is an unmodified installation of
Debian and Proxmox packages, so it points at those archives for the
corresponding source, and records that the firmware licence texts ship inside the
image at /usr/share/doc/pve-firmware/licenses/ and must not be stripped.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

scripts/ci/publish-release.sh

@@ -0,0 +1,75 @@
+#!/bin/bash
+# Copyright (C) 2026 Ilker Manap
+# SPDX-License-Identifier: AGPL-3.0-or-later
+#
+# Creates a Gitea release and uploads the image, its checksum and the
+# corresponding-source offer.
+#
+#   publish-release.sh <tag> <version> <dist-dir>
+#
+# Requires GITEA_API and GITEA_TOKEN in the environment.
+set -euo pipefail
+
+TAG="${1:?tag required}"
+VERSION="${2:?version required}"
+DIST="${3:?dist directory required}"
+: "${GITEA_API:?GITEA_API required}"
+: "${GITEA_TOKEN:?GITEA_TOKEN required}"
+
+REPO_URL="${GITHUB_SERVER_URL:-}/${GITHUB_REPOSITORY:-}"
+RUN="${GITHUB_RUN_NUMBER:-manual}"
+SHA="${GITHUB_SHA:-}"
+IMAGE=$(basename "$(ls "$DIST"/maas-image-*.tar.gz)")
+
+BODY=$(cat <<BODYEOF
+Unofficial build of a MAAS-deployable Proxmox VE image.
+**Not affiliated with or endorsed by Proxmox Server Solutions GmbH.**
+
+- pve-manager: \`${VERSION}\`
+- Built: $(date -u +%Y-%m-%dT%H:%M:%SZ), run ${RUN}
+- Verify: \`sha256sum -c ${IMAGE}.sha256\`
+
+Upload to MAAS:
+
+\`\`\`bash
+maas \$PROFILE boot-resources create name='custom/proxmox-ve-9' \\
+    title='Proxmox VE 9' architecture='amd64/generic' \\
+    filetype='tgz' content@=${IMAGE}
+\`\`\`
+
+The curtin preseed from this repository must also be installed on the MAAS region
+controller, otherwise deployment fails — see the README.
+
+\`SOURCES.md\` in this release carries the corresponding-source offer required by
+the GPL/AGPL licences of the packages inside the image.
+BODYEOF
+)
+
+PAYLOAD=$(TAG="$TAG" VERSION="$VERSION" BODY="$BODY" SHA="$SHA" python3 -c '
+import json, os
+print(json.dumps({
+    "tag_name": os.environ["TAG"],
+    "name": "Proxmox VE %s image" % os.environ["VERSION"],
+    "body": os.environ["BODY"],
+    "draft": False,
+    "prerelease": False,
+    "target_commitish": os.environ["SHA"],
+}))')
+
+ID=$(curl -fsS -X POST \
+        -H "Authorization: token ${GITEA_TOKEN}" \
+        -H 'Content-Type: application/json' \
+        -d "$PAYLOAD" "${GITEA_API}/releases" \
+     | python3 -c 'import json,sys; print(json.load(sys.stdin)["id"])')
+echo "release id: ${ID}"
+
+for f in "$DIST"/*; do
+    [ -f "$f" ] || continue
+    echo "uploading $(basename "$f") ($(du -h "$f" | cut -f1))"
+    curl -fsS -X POST \
+        -H "Authorization: token ${GITEA_TOKEN}" \
+        -F "attachment=@${f}" \
+        "${GITEA_API}/releases/${ID}/assets?name=$(basename "$f")" >/dev/null
+done
+
+echo "published: ${REPO_URL}/releases/tag/${TAG}"