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/separator.tsx

@@ -0,0 +1,28 @@
+"use client"
+
+import * as React from "react"
+import * as SeparatorPrimitive from "@radix-ui/react-separator"
+
+import { cn } from "@/lib/utils"
+
+function Separator({
+  className,
+  orientation = "horizontal",
+  decorative = true,
+  ...props
+}: React.ComponentProps<typeof SeparatorPrimitive.Root>) {
+  return (
+    <SeparatorPrimitive.Root
+      data-slot="separator"
+      decorative={decorative}
+      orientation={orientation}
+      className={cn(
+        "bg-border shrink-0 data-[orientation=horizontal]:h-px data-[orientation=horizontal]:w-full data-[orientation=vertical]:h-full data-[orientation=vertical]:w-px",
+        className
+      )}
+      {...props}
+    />
+  )
+}
+
+export { Separator }