feat: enhance dashboard layout and UI components for improved responsiveness

- Introduce new 'xs' screen size in Tailwind configuration for better mobile support
- Update dashboard layout to use a cosmic gradient background for a modern look
- Refactor Quick Actions component for improved styling and layout consistency
- Add Current Open Invoice Card for quick access to ongoing invoices
- Standardize button sizes across various components for a cohesive user experience
- Implement responsive design adjustments in invoice forms and data tables

This update enhances the overall user experience by improving responsiveness and visual appeal across the dashboard and related components.

src/app/dashboard/layout.tsx

@@ -8,23 +8,23 @@ export default function DashboardLayout({
   children: React.ReactNode;
 }) {
   return (
-    <>
+    <div className="bg-cosmic-gradient bg-nebula-overlay relative min-h-screen">
       <Navbar />
       <Sidebar />
       {/* Mobile layout - no left margin */}
-      <main className="min-h-screen pt-20 md:hidden">
+      <main className="relative z-10 min-h-screen pt-20 md:hidden">
         <div className="px-4 pt-4 pb-6 sm:px-6">
           <DashboardBreadcrumbs />
           {children}
         </div>
       </main>
       {/* Desktop layout - with sidebar margin */}
-      <main className="hidden min-h-screen pt-20 md:ml-[276px] md:block">
+      <main className="relative z-10 hidden min-h-screen pt-20 md:ml-[276px] md:block">
         <div className="px-6 pt-6 pb-6">
           <DashboardBreadcrumbs />
           {children}
         </div>
       </main>
-    </>
+    </div>
   );
 }