Show category and publisher descriptions on the game detail page

The categories and publishers tables already include a description field, but the game detail page only shows their names. Surfacing these descriptions gives backers helpful context about who is behind a game and what kind of game it is, with no schema changes required.

Acceptance criteria

• The game detail page displays the category description when one is available
• The game detail page displays the publisher description when one is available
• Missing descriptions are handled gracefully (the section is hidden rather than showing empty content)
• The new content follows the project's styling and accessibility guidelines and includes data-testid attributes
• The data-access helper is updated to include the description fields, with unit tests covering the change, and Playwright e2e tests verify the descriptions render

Start at the game detail page and trace the data-access helper that supplies category and publisher data. Update the helper and its unit tests, then add the requested rendering and Playwright e2e coverage. Done means available descriptions render with data-testid attributes, while missing descriptions hide their sections and the styling remains accessible.