Add GitHub Actions workflow to mirror to Gitea

.github/workflows/mirror-to-gittea.yml

@@ -0,0 +1,24 @@
+name: Mirror to Gitea
+
+on:
+  push:
+  workflow_dispatch:
+
+jobs:
+  mirror:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Mirror to Gitea
+        env:
+          GITEA_URL: ${{ secrets.GITEA_URL }}
+          GITEA_USERNAME: ${{ secrets.GITEA_USERNAME }}
+          GITEA_TOKEN: ${{ secrets.GITEA_TOKEN }}
+        run: |
+          git remote add gitea https://${GITEA_USERNAME}:${GITEA_TOKEN}@${GITEA_URL}
+          git push --quiet --mirror gitea