Fix Gitea Actions: replace actions/checkout with manual git clone

Runner job containers cannot resolve internal 'gitea' hostname.
Use public URL (git.produktor.io) for checkout instead.

Co-authored-by: Cursor <cursoragent@cursor.com>

.github/workflows/release.yaml

@@ -27,7 +27,9 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: https://github.com/actions/checkout@v4
+        run: |
+          git clone --depth=1 https://git.produktor.io/${{ gitea.repository }}.git .
+          git checkout ${{ gitea.sha }}
 
       - name: Install Helm
         run: |
@@ -49,9 +51,9 @@ jobs:
       contents: write
     steps:
       - name: Checkout
-        uses: https://github.com/actions/checkout@v4
-        with:
-          fetch-depth: 0
+        run: |
+          git clone https://git.produktor.io/${{ gitea.repository }}.git .
+          git checkout ${{ gitea.sha }}
 
       - name: Install Helm
         run: |