Move Gateway up in nav; render jobs and programs as cards

Reorder the sidebar so Gateway sits right under Overview. Replace the
Scheduled and Program tables with card grids matching Services: add JobCard
and ProgramCard, convert ScheduledSection to a JobCard grid, and turn the
former ProgramTable into a filterable ProgramCard grid (renamed ProgramList;
kept the search box, dropped the sortable table). Remove the now-orphaned
SortHeader component.

app/src/components/Layout.tsx

@@ -17,10 +17,10 @@ import { useEventStream } from "@/services/api/hooks"
 
 const NAV = [
   { to: "/", label: "Overview", icon: LayoutDashboard, end: true },
+  { to: "/gateway", label: "Gateway", icon: Globe, end: false },
   { to: "/services", label: "Services", icon: Server, end: false },
   { to: "/scheduled", label: "Scheduled", icon: Clock, end: false },
   { to: "/programs", label: "Programs", icon: Package, end: false },
-  { to: "/gateway", label: "Gateway", icon: Globe, end: false },
   { to: "/mesh", label: "Mesh", icon: Share2, end: false },
 ]