Fix nginx config validation method

- Use proper nginx -t instead of -c option
- Test by temporarily applying config, then restore
- Validates against full nginx context

🤖 Generated with [Claude Code](https://claude.ai/code)

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

.gitea/workflows/deploy.yml

@@ -45,12 +45,17 @@ jobs:
       - name: Validate new nginx configuration
         run: |
           echo "🔍 Validating new nginx configuration syntax..."
-          # Create temporary copy to validate
-          sudo cp server-nginx-default /tmp/nginx-test-config
-          sudo nginx -t -c /tmp/nginx-test-config || {
+          # Backup current config and test with new one
+          sudo cp /etc/nginx/sites-available/default /etc/nginx/sites-available/default.temp.backup
+          sudo cp server-nginx-default /etc/nginx/sites-available/default
+          sudo nginx -t || {
             echo "❌ New nginx configuration has syntax errors!"
+            # Restore backup
+            sudo cp /etc/nginx/sites-available/default.temp.backup /etc/nginx/sites-available/default
             exit 1
           }
+          # Restore backup for now (will apply later)
+          sudo cp /etc/nginx/sites-available/default.temp.backup /etc/nginx/sites-available/default
           echo "✅ New configuration syntax is valid"
           
       - name: Apply new nginx configuration