refactor: Remove Scaffold from page bodies

- Removed unnecessary Scaffold
- Simplified page structure

Author: fulleni

lib/content_management/view/categories_page.dart

@@ -9,10 +9,8 @@ class CategoriesPage extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    return const Scaffold(
-      body: Center(
-        child: Text('Categories Page'),
-      ),
+    return const Center(
+      child: Text('Categories Page'),
     );
   }
 }

lib/content_management/view/headlines_page.dart

@@ -9,10 +9,8 @@ class HeadlinesPage extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    return const Scaffold(
-      body: Center(
-        child: Text('Headlines Page'),
-      ),
+    return const Center(
+      child: Text('Headlines Page'),
     );
   }
 }

lib/content_management/view/sources_page.dart

@@ -9,10 +9,8 @@ class SourcesPage extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    return const Scaffold(
-      body: Center(
-        child: Text('Sources Page'),
-      ),
+    return const Center(
+      child: Text('Sources Page'),
     );
   }
 }