CI: replace checkout action with direct git clone (no node in container)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

.gitea/workflows/release.yml

@@ -10,11 +10,16 @@ jobs:
     container:
       image: eclipse-temurin:21-jdk
     steps:
-      - uses: actions/checkout@v4
+      # actions/checkout needs node, which this container lacks — clone directly
+      - name: Checkout
+        run: |
+          apt-get update -qq && apt-get install -y -qq git unzip curl >/dev/null
+          git init -q .
+          git fetch -q --depth 1 "${{ github.server_url }}/${{ github.repository }}.git" "${{ github.sha }}"
+          git checkout -q FETCH_HEAD
 
       - name: Install Android SDK
         run: |
-          apt-get update -qq && apt-get install -y -qq unzip curl >/dev/null
           mkdir -p "$HOME/android-sdk/cmdline-tools"
           curl -sLo /tmp/ct.zip https://dl.google.com/android/repository/commandlinetools-linux-11076708_latest.zip
           unzip -q /tmp/ct.zip -d /tmp