init: arcadia-admin — admin webapp for arcadia-core, cloned from vibespace

Initial commit. Spun up via the docs/STARTER.md recipe: cp from vibespace,
reset git, rename package, set brand to "Arcadia Admin" with Shield icon
in app/lib/identity.ts.

Inherits the full Crema sibling-lib wiring including @crema/arcadia-client
(typed HTTP + Phoenix Channels realtime against arcadia-core) and
@crema/arcadia-auth-ui (login/signup/password-reset/2FA forms). The /login
route already renders <LoginForm>; <ArcadiaProvider> in app/root.tsx reads
VITE_ARCADIA_URL (default localhost:4000) and VITE_ARCADIA_TENANT (default
"default").

CLAUDE.md and README rewritten to frame this as the admin app for
arcadia-core. docs/STARTER.md removed — arcadia-admin is a leaf consumer,
not a downstream starter.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

app/components/layout/appbar.tsx

@@ -0,0 +1,48 @@
+import type { ComponentProps } from "react"
+
+import { cn } from "~/lib/utils"
+
+function Appbar({ className, ...props }: ComponentProps<"header">) {
+  return (
+    <header
+      data-slot="appbar"
+      className={cn(
+        "flex h-14 w-full items-center gap-3 border-b bg-background px-4",
+        className
+      )}
+      {...props}
+    />
+  )
+}
+
+function AppbarTitle({ className, ...props }: ComponentProps<"span">) {
+  return (
+    <span
+      data-slot="appbar-title"
+      className={cn("font-heading text-sm font-semibold", className)}
+      {...props}
+    />
+  )
+}
+
+function AppbarSpacer({ className, ...props }: ComponentProps<"div">) {
+  return (
+    <div
+      data-slot="appbar-spacer"
+      className={cn("flex-1", className)}
+      {...props}
+    />
+  )
+}
+
+function AppbarActions({ className, ...props }: ComponentProps<"div">) {
+  return (
+    <div
+      data-slot="appbar-actions"
+      className={cn("flex items-center gap-1", className)}
+      {...props}
+    />
+  )
+}
+
+export { Appbar, AppbarTitle, AppbarSpacer, AppbarActions }