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/routes/activity.tsx

@@ -0,0 +1,43 @@
+import { Activity } from "lucide-react"
+
+import { AppShell } from "~/components/layout/app-shell"
+import {
+  Card,
+  CardContent,
+  CardDescription,
+  CardHeader,
+  CardTitle,
+} from "~/components/ui/card"
+import { pageTitle } from "~/lib/page-meta"
+
+export const meta = () => pageTitle("Activity")
+
+export default function ActivityRoute() {
+  return (
+    <AppShell title="Activity">
+      <Card>
+        <CardHeader>
+          <CardTitle>Activity</CardTitle>
+          <CardDescription>
+            Event stream, audit log, recent changes.
+          </CardDescription>
+        </CardHeader>
+        <CardContent>
+          <div className="flex flex-col items-center justify-center gap-3 rounded-lg border-2 border-dashed border-muted-foreground/20 bg-muted/30 p-12 text-center">
+            <div className="flex size-12 items-center justify-center rounded-xl bg-background text-muted-foreground">
+              <Activity className="size-6" />
+            </div>
+            <div className="max-w-md">
+              <p className="font-medium">No activity yet</p>
+              <p className="mt-1 text-sm text-muted-foreground">
+                Once your app is doing things, this is where audit events,
+                webhook deliveries, and recent changes show up — pair with{" "}
+                <code className="font-mono text-xs">@crema/log-ui</code>.
+              </p>
+            </div>
+          </div>
+        </CardContent>
+      </Card>
+    </AppShell>
+  )
+}