feat: add build hash to sidebar footer and Gitea CI/CD deploy workflow

- Inject git commit short hash at build time via NEXT_PUBLIC_BUILD_HASH
- Display build hash in sidebar footer for version tracking
- Add Gitea Actions workflow to auto-deploy on push to master (SSH → pull → rebuild)

Co-Authored-By: Paperclip <noreply@paperclip.ing>

.gitea/workflows/deploy.yml

@@ -0,0 +1,24 @@
+name: Deploy to VPS
+
+on:
+  push:
+    branches:
+      - master
+
+jobs:
+  deploy:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Deploy via SSH
+        uses: appleboy/ssh-action@v1
+        with:
+          host: ${{ secrets.VPS_HOST }}
+          username: ${{ secrets.VPS_USER }}
+          key: ${{ secrets.VPS_SSH_KEY }}
+          port: ${{ secrets.VPS_PORT || 22 }}
+          script: |
+            cd ${{ secrets.VPS_PROJECT_PATH || '/opt/legalai' }}
+            git pull origin master
+            docker compose build app
+            docker compose up -d app
+            echo "Deployed commit: $(git rev-parse --short HEAD)"