fix: replace actions/checkout with git clone (no node on runner)

The linux runner has no Node.js, so actions/checkout@v4 fails.
Use manual git clone with token auth instead.

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

.gitea/workflows/ci.yaml

@@ -8,7 +8,10 @@ jobs:
   test:
     runs-on: linux
     steps:
-      - uses: actions/checkout@v4
+      - run: |
+          git clone --depth 1 \
+            -c "http.extraHeader=Authorization: token ${{ github.token }}" \
+            "${{ github.server_url }}/${{ github.repository }}.git" .
       - run: |
           podman run --rm \
             -v "$PWD:/app:ro" \
@@ -21,9 +24,10 @@ jobs:
   secrets:
     runs-on: linux
     steps:
-      - uses: actions/checkout@v4
-        with:
-          fetch-depth: 0
+      - run: |
+          git clone \
+            -c "http.extraHeader=Authorization: token ${{ github.token }}" \
+            "${{ github.server_url }}/${{ github.repository }}.git" .
       - run: |
           podman run --rm \
             -v "$PWD:/scan:ro" \
@@ -34,7 +38,10 @@ jobs:
     needs: [test, secrets]
     runs-on: linux
     steps:
-      - uses: actions/checkout@v4
+      - run: |
+          git clone --depth 1 \
+            -c "http.extraHeader=Authorization: token ${{ github.token }}" \
+            "${{ github.server_url }}/${{ github.repository }}.git" .
       - run: echo "$HARBOR_PASS" | podman login -u "$HARBOR_USER" --password-stdin harbor.mymx.me
         env:
           HARBOR_USER: ${{ secrets.HARBOR_USER }}