Add a second tab in the node Icon picker to choose from the ~2250 brand
icons hosted by homarr-labs/dashboard-icons (Plex, Sonarr, Home
Assistant, etc.) served via jsDelivr CDN. The Generic tab keeps the
existing lucide picker unchanged.
Storage uses a 'brand:<slug>' prefix on custom_icon, so existing nodes
referencing lucide keys keep working with zero migration. A new
resolveCustomIcon helper returns a discriminated union (lucide | brand)
and a NodeIcon component centralizes rendering for both kinds.
Includes a manifest fetch script (scripts/fetch-dashboard-icons.mjs)
and a checked-in dashboardIcons.json snapshot.