TASK-017, human product owner priority-1 request. Repository list now
requests sort=updated&order=desc from Gitea, loads 5 repositories per
page with explicit prev/next navigation, and each visible row
independently fetches and shows its most recently committed branch.
Removes the legacy eager-loading RepositoryListApi in favor of the
existing paged GiteaRepositoryBrowser.listRepositories. Fixes two
issues found in self-review: missing error handling on page
navigation, and repositories with no default branch (empty repos)
previously failing the whole page instead of just that row.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
