ci: add workflow to sync repository to CNB.cool

Add GitHub workflow to automatically sync changes to CNB.cool mirror repository on push events.

Signed-off-by: longjin <[email protected]>

Author: fslongjin

.github/workflows/sync-to-cnb-cool.yml

@@ -0,0 +1,23 @@
+name: Sync to CNB.cool
+on: [push]
+
+jobs:
+  sync:
+    if: github.repository == 'DragonOS-Community/gvisor'
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+        with:
+          fetch-depth: 0
+      
+      - name: Sync to CNB Repository
+        run: |
+          docker run --rm \
+            -v ${{ github.workspace }}:${{ github.workspace }} \
+            -w ${{ github.workspace }} \
+            -e PLUGIN_TARGET_URL="https://cnb.cool/DragonOS-Community/gvisor.git" \
+            -e PLUGIN_AUTH_TYPE="https" \
+            -e PLUGIN_USERNAME="cnb" \
+            -e PLUGIN_PASSWORD=${{ secrets.CNB_GIT_PASSWORD }} \
+            -e PLUGIN_FORCE="true" \
+            docker.cnb.cool/fslongjin/git-sync:250626