Fix footer floating mid-page on short content pages

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/components/Layout.tsx

@@ -5,7 +5,7 @@ export function Layout() {
   const [menuOpen, setMenuOpen] = useState(false)
 
   return (
-    <div className="min-h-screen bg-gray-50 dark:bg-gray-900 text-gray-900 dark:text-gray-100">
+    <div className="min-h-screen flex flex-col bg-gray-50 dark:bg-gray-900 text-gray-900 dark:text-gray-100">
       <nav className="bg-white dark:bg-gray-800 shadow-sm">
         <div className="max-w-7xl mx-auto px-4 sm:px-6 lg:px-8">
           <div className="flex justify-between h-16">
@@ -124,7 +124,7 @@ export function Layout() {
           </div>
         )}
       </nav>
-      <main>
+      <main className="flex-1">
         <Outlet />
       </main>
       <footer className="border-t border-gray-200 dark:border-gray-700 bg-white dark:bg-gray-800">