Phase 3a: shadcn init + Home/Case List view

Initialize shadcn/ui (radix-nova preset) and wire its semantic tokens
to the editorial navy/cream/gold palette so primitives inherit the
judicial voice without per-component overrides.

Replace the Phase 2 live-probe with a real dashboard: KPI tiles,
conic-gradient status donut (ported from the vanilla renderHero),
and a TanStack Table cases list with search + sort. Add useCase(n)
hook with 5s staleTime/refetchInterval to replace the old manual
polling loop when Case Detail ships next.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

web-ui/src/components/ui/separator.tsx

@@ -0,0 +1,28 @@
+"use client"
+
+import * as React from "react"
+import { Separator as SeparatorPrimitive } from "radix-ui"
+
+import { cn } from "@/lib/utils"
+
+function Separator({
+  className,
+  orientation = "horizontal",
+  decorative = true,
+  ...props
+}: React.ComponentProps<typeof SeparatorPrimitive.Root>) {
+  return (
+    <SeparatorPrimitive.Root
+      data-slot="separator"
+      decorative={decorative}
+      orientation={orientation}
+      className={cn(
+        "shrink-0 bg-border data-horizontal:h-px data-horizontal:w-full data-vertical:w-px data-vertical:self-stretch",
+        className
+      )}
+      {...props}
+    />
+  )
+}
+
+export { Separator }