Replace inline fmt.Sprintf HTML generation in Dashboard, ListIssues,
and ListPulls handlers with template.ParseFiles rendering of
dashboard.html, issues.html, and pulls.html respectively.
ListIssues now reads ?org= and ?state= query params to filter results.
ListPulls now reads ?org= query param to filter results.
Closesleeworks-agents/gitea-mobile#34
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>