refactor: enhance Sidebar layout with fixed header and footer, improve dashboard layout, and implement symbol management features including deletion and data display

apps/web/src/routes/(dashboard)/+layout.svelte

@@ -2,10 +2,10 @@
   const { children } = $props();
 </script>
 
-<div class="max-w-[1600px w-full">
+<div class="w-full">
   <main
     id="container-central"
-    class="m-3 rounded-xl shadow-sm overflow-y-auto p-4"
+    class="container mx-auto p-4 lg:p-6 max-w-7xl"
   >
     {@render children()}
   </main>