Add "View all" links to the Purchases / Sessions / Play Events sections
on the game-detail page, each pointing at the matching filtered list view
via filter_url(). Pure consumer of the #56 filter_url()/where() helpers;
no new filter machinery.
- _game_section() gains an optional view_all_url, rendered as a gray xs
button beside the heading (shown only when the section is non-empty).
- New arrowright icon for the link.
- Tests: each section renders the expected escaped href; a parity test
asserts each link's filter scopes to the game and excludes others.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
