fix(panel): pin sidebar navigation and enable independent content scroll

panel/src/components/AppShell.tsx

@@ -151,7 +151,7 @@ export function AppShell() {
   }, [i18n.language, t]);
 
   return (
-    <div className="flex min-h-screen">
+    <div className="flex h-screen overflow-hidden">
       <aside className="hidden w-60 shrink-0 flex-col border-r border-border bg-card/40 p-4 md:flex">
         <div className="mb-6 flex items-center gap-2 px-2">
           <Cat className="h-6 w-6 text-primary" />
@@ -186,7 +186,7 @@ export function AppShell() {
         </div>
       </aside>
 
-      <div className="flex min-w-0 flex-1 flex-col">
+      <div className="flex min-w-0 flex-1 flex-col h-full overflow-y-auto">
         <header className="flex h-14 items-center justify-between border-b border-border px-4 md:hidden">
           <div className="flex items-center gap-2">
             <Cat className="h-5 w-5 text-primary" />