Update frontend dependencies, enhance Vite configuration, and refactor components

- Added new dependencies including @base-ui/react, @fontsource-variable/geist, and tailwindcss for improved UI and styling.
- Updated Vite configuration to include path aliasing for easier imports.
- Refactored App.jsx to implement a theme context and improved routing structure.
- Enhanced various components (e.g., ConfirmDialog, DataTable) to utilize new UI components and improve user experience.
- Cleaned up CSS imports and ensured proper styling integration.

Made-with: Cursor

frontend/src/components/ui/skeleton.tsx

@@ -0,0 +1,13 @@
+import { cn } from "@/lib/utils"
+
+function Skeleton({ className, ...props }: React.ComponentProps<"div">) {
+  return (
+    <div
+      data-slot="skeleton"
+      className={cn("animate-pulse rounded-md bg-muted", className)}
+      {...props}
+    />
+  )
+}
+
+export { Skeleton }