packaging(flatpak): add OCI image build and GHCR publishing helper (#4987)

packaging/linux/flatpak-bundle.sh

@@ -20,10 +20,12 @@ APP_ID=ai.storyteller.vectorcraft
 FLATHUB=https://dl.flathub.org/repo/flathub.flatpakrepo
 
 TEST=1
+OCI=0
 TARBALL=""
 while [[ $# -gt 0 ]]; do
   case "$1" in
     --no-test) TEST=0; shift ;;
+    --oci) OCI=1; shift ;;
     -h | --help) sed -n '2,14p' "$0"; exit 0 ;;
     -*) echo "unknown argument: $1" >&2; exit 2 ;;
     *) TARBALL="$1"; shift ;;
@@ -61,6 +63,12 @@ OUT="$DIST/$BASENAME.flatpak"
 # --runtime-repo lets `flatpak install` fetch the freedesktop runtime from Flathub if missing.
 flatpak build-bundle --runtime-repo="$FLATHUB" "$WORK/repo" "$OUT" "$APP_ID" stable
 echo "wrote $OUT"
+if [[ "$OCI" = 1 ]]; then
+  OUT_OCI="$DIST/$BASENAME-oci"
+  rm -rf "$OUT_OCI"
+  flatpak build-bundle --oci "$WORK/repo" "$OUT_OCI" "$APP_ID" stable
+  echo "wrote OCI layout to $OUT_OCI"
+fi
 
 if [[ "$TEST" = 1 ]]; then
   flatpak install --user -y --noninteractive --reinstall "$OUT"