Improve pet habitat UX with ground-aligned walk, floating rename, and demo points.

Anchor room floors on resize, constrain wandering to a ground zone, add an editable floating name badge on the avatar screen, and let profile demo tools grant 100 test points.

components/pet/pet-ground-zone.tsx

@@ -0,0 +1,20 @@
+"use client";
+
+import { PET_GROUND_ZONE_HEIGHT_RATIO } from "@/lib/pet-wander-bounds";
+import { cn } from "@/lib/utils";
+
+type PetGroundZoneProps = {
+  children: React.ReactNode;
+  className?: string;
+};
+
+export function PetGroundZone({ children, className }: PetGroundZoneProps) {
+  return (
+    <div
+      className={cn("absolute inset-x-0 bottom-0 z-10", className)}
+      style={{ height: `${PET_GROUND_ZONE_HEIGHT_RATIO * 100}%` }}
+    >
+      {children}
+    </div>
+  );
+}