fix(ci): replace actions/checkout@v4 in deploy job with shell git

Node.js is not in PATH on the self-hosted:host runner, so JS actions
(actions/checkout@v4) fail with "cannot find node". Use the same shell
git init/fetch/checkout pattern used in all other jobs.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitea/workflows/ci-cd.yml

@@ -277,7 +277,16 @@ jobs:
     timeout-minutes: 40
 
     steps:
-      - uses: actions/checkout@v4
+      - name: Checkout
+        env:
+          TOKEN: ${{ github.token }}
+          REF: ${{ github.ref }}
+        run: |
+          git init
+          git remote add origin "${{ github.server_url }}/${{ github.repository }}.git"
+          git config http.extraheader "Authorization: Bearer ${TOKEN}"
+          git fetch --depth=1 origin "${REF}"
+          git checkout FETCH_HEAD
 
       - name: Write .env
         run: printf '%s' "$ENV_FILE" > .env