ci: add production deploy workflow

Triggers update watchdog on production server via SSH on every push to main.

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

.github/workflows/deploy.yml

@@ -0,0 +1,20 @@
+name: Deploy to Production
+
+on:
+  push:
+    branches: [main]
+
+jobs:
+  deploy:
+    name: Trigger production update
+    runs-on: ubuntu-latest
+    needs: []
+    steps:
+      - name: SSH and trigger update
+        uses: appleboy/ssh-action@v1
+        with:
+          host: ${{ secrets.PROD_HOST }}
+          username: ${{ secrets.PROD_USER }}
+          key: ${{ secrets.PROD_SSH_KEY }}
+          port: ${{ secrets.PROD_PORT || 22 }}
+          script: touch ${{ secrets.PROD_PROJECT_DIR }}/.update_trigger