fix: replace motion/react imports with framer-motion + rounded content panel

- 4 files imported from 'motion/react' which was the removed 'motion' package.
  Replaced with 'framer-motion' (the package actually installed).
- Dashboard content area now has rounded corners, subtle border, and inset
  margin creating a "panel inside shell" visual separation from the sidebar.

components/dashboard/DashboardShell.tsx

@@ -31,14 +31,15 @@ export default function DashboardShell({
   const openMobile = useCallback(() => setMobileOpen(true), [])
 
   return (
-    <div className="flex h-screen overflow-hidden">
+    <div className="flex h-screen overflow-hidden bg-neutral-950">
       <Sidebar
         siteId={siteId}
         mobileOpen={mobileOpen}
         onMobileClose={closeMobile}
         onMobileOpen={openMobile}
       />
-      <div className="flex-1 flex flex-col min-w-0 overflow-hidden">
+      {/* Content panel — rounded on all corners with slight inset to separate from sidebar */}
+      <div className="flex-1 flex flex-col min-w-0 overflow-hidden my-2 mr-2 rounded-2xl bg-neutral-900 border border-neutral-800/60">
         <ContentHeader onMobileMenuOpen={openMobile} />
         <main className="flex-1 overflow-y-auto pt-4">
           {children}