Add server-side table sorting

[lovasoa]

Closes #1442

Summary

• add opt-in server_sort_column table headers that reload with sort_<column>=ASCENDING|DESCENDING
• preserve existing in-browser sort behavior for other columns
• document the property and use it in the simple website example

Testing

• npm test
• npx playwright test fixtures/table-server-sort/test.ts --project=fixtures --reporter=line
• hurl --test --error-format long examples/simple-website-example/test.hurl