ci: fetch source without node-based checkout action

.gitea/workflows/release-container.yml

@@ -14,8 +14,22 @@ jobs:
     name: Build and push image
     runs-on: linux_amd64
     steps:
-      - name: Check out repository
-        uses: actions/checkout@v4
+      - name: Fetch tagged source
+        id: checkout
+        shell: bash
+        run: |
+          set -euo pipefail
+          repo_url="${GITHUB_SERVER_URL:-http://192.168.33.22:3300}/gemma/arcana-fx.git"
+          tag="${GITHUB_REF_NAME:-${GITEA_REF_NAME:-}}"
+          workdir="$(mktemp -d)"
+
+          if [ -z "$tag" ]; then
+            echo "missing tag name in workflow environment" >&2
+            exit 1
+          fi
+
+          git clone --depth 1 --branch "$tag" "$repo_url" "$workdir/repo"
+          echo "dir=$workdir/repo" >> "$GITHUB_OUTPUT"
 
       - name: Derive image coordinates
         id: meta
@@ -49,7 +63,7 @@ jobs:
           docker build \
             --tag "${{ steps.meta.outputs.image }}:${{ steps.meta.outputs.tag }}" \
             --tag "${{ steps.meta.outputs.image }}:latest" \
-            .
+            "${{ steps.checkout.outputs.dir }}"
 
       - name: Push image tags
         shell: bash