feat: add UI components including Skeleton, Slider, Toaster, Switch, Table, Tabs, Textarea, Toggle Group, Toggle, Tooltip, and User Avatar

- Implemented Skeleton component for loading states.
- Added Slider component using Radix UI for customizable sliders.
- Created Toaster component for notifications with theme support.
- Developed Switch component for toggle functionality.
- Introduced Table component with subcomponents for structured data display.
- Built Tabs component for tabbed navigation.
- Added Textarea component for multi-line text input.
- Implemented Toggle Group and Toggle components for grouped toggle buttons.
- Created Tooltip component for displaying additional information on hover.
- Added User Avatar component for displaying user images with fallback.
- Implemented useIsMobile hook for responsive design.
- Created API utility functions for user and thought data fetching.
- Added utility function for class name merging.
- Updated package.json with new dependencies for UI components and utilities.
- Added TypeScript configuration for path aliasing.

thoughts-frontend/components/ui/aspect-ratio.tsx

@@ -0,0 +1,11 @@
+"use client"
+
+import * as AspectRatioPrimitive from "@radix-ui/react-aspect-ratio"
+
+function AspectRatio({
+  ...props
+}: React.ComponentProps<typeof AspectRatioPrimitive.Root>) {
+  return <AspectRatioPrimitive.Root data-slot="aspect-ratio" {...props} />
+}
+
+export { AspectRatio }