refactor(layouts): simplify MainLayout and enhance styling

- Removed unused imports and performance monitoring hooks from MainLayout.
- Updated layout structure to improve responsiveness and styling, including sticky header and optimized content padding.
- Adjusted home page layout to reduce margin and improve spacing for better visual consistency.
- Enhanced TodoList component with collapsible sections for improved user interaction and task management.
- Streamlined project and schedule pages by removing unnecessary margin adjustments, ensuring a cleaner layout.

worklenz-frontend/src/pages/schedule/schedule.tsx

@@ -54,7 +54,7 @@ const Schedule: React.FC = () => {
   };
 
   return (
-    <div style={{ marginBlockStart: 65, minHeight: '90vh' }}>
+    <div style={{ minHeight: '90vh' }}>
       <Flex align="center" justify="space-between">
         <Flex
           gap={16}