feat(sponsor-panel): redesign dashboard as tabbed admin panel
Replace the multi-card dashboard with a sidebar-tab layout so every
benefit lives on its own panel instead of competing for space in a
2-column grid. Tabs group by purpose (Account / Benefits / Developer)
and the active tab is remembered via URL hash and localStorage, with
arrow-key navigation across the tablist.
Each panel now carries a consistent header (icon tile + serif title +
subtitle), the sponsorship tab surfaces monthly amount and tier as
stat cards, logo submission uses a proper drag-and-drop zone, and a
bottom-center toast confirms HTMX form successes. All existing form
posts (/invite, /logo, /thoth-token) are preserved; no backend or
route changes.
Non-sponsors see only the Sponsorship tab with the upgrade CTA.
$50+ sponsors get the Team Invitations tab added to the Benefits
group.
Based on a Claude Design handoff bundle.
Assisted-by: Claude Opus 4.7 via Claude Code
Signed-off-by: Xe Iaso <me@xeiaso.net>