Improve layout and add auction functionality for media outlets

Refactor MainContent, AdminDashboard, and MediaOutlet components to enforce a sticky footer, adjust layout for header elements, and prepare for the integration of auction features.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: 069d4324-6c40-4355-955e-c714a50de1ea
Replit-Commit-Checkpoint-Type: intermediate_checkpoint
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/3df548ff-50ae-432f-9be4-25d34eccc983/069d4324-6c40-4355-955e-c714a50de1ea/Ml7hyYJ

client/src/components/MainContent.tsx

@@ -86,8 +86,8 @@ export default function MainContent() {
   );
 
   return (
-    <div className="min-h-screen bg-gray-50">
-      <div className="max-w-7xl mx-auto px-4 py-4">
+    <div className="flex flex-col min-h-screen bg-gray-50">
+      <div className="flex-1 max-w-7xl mx-auto px-4 py-4 w-full">
         {isLoading ? (
           <div className="grid grid-cols-1 lg:grid-cols-3 gap-6">
             {categories.map((category) => (