ci: add Gitea Actions workflow for deploying to onixbyte.cn

Sync doc_build/ to the onixbyte.cn server via rsync over SSH.

.gitea/workflows/deploy-onixbyte.yml

@@ -0,0 +1,34 @@
+name: Deploy to OnixByte.cn
+
+on:
+  push:
+    branches: [main]
+  workflow_dispatch:
+
+jobs:
+  deploy:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: 22
+
+      - name: Install pnpm
+        run: npm install -g pnpm
+
+      - name: Install dependencies
+        run: pnpm install --frozen-lockfile
+
+      - name: Build
+        run: pnpm build
+
+      - name: Deploy to OnixByte.cn
+        run: |
+          mkdir -p ~/.ssh
+          echo "${{ secrets.DEPLOY_SSH_KEY }}" > ~/.ssh/id_ed25519
+          chmod 600 ~/.ssh/id_ed25519
+          ssh-keyscan onixbyte.cn >> ~/.ssh/known_hosts
+          rsync -avz --delete doc_build/ root@onixbyte.cn:${{ vars.DEPLOY_PATH }}