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/input.tsx

@@ -0,0 +1,21 @@
+import * as React from "react"
+
+import { cn } from "@/lib/utils"
+
+function Input({ className, type, ...props }: React.ComponentProps<"input">) {
+  return (
+    <input
+      type={type}
+      data-slot="input"
+      className={cn(
+        "file:text-foreground placeholder:text-muted-foreground selection:bg-primary selection:text-primary-foreground dark:bg-input/30 border-input flex h-9 w-full min-w-0 rounded-md border bg-transparent px-3 py-1 text-base shadow-xs transition-[color,box-shadow] outline-none file:inline-flex file:h-7 file:border-0 file:bg-transparent file:text-sm file:font-medium disabled:pointer-events-none disabled:cursor-not-allowed disabled:opacity-50 md:text-sm",
+        "focus-visible:border-ring focus-visible:ring-ring/50 focus-visible:ring-[3px]",
+        "aria-invalid:ring-destructive/20 dark:aria-invalid:ring-destructive/40 aria-invalid:border-destructive",
+        className
+      )}
+      {...props}
+    />
+  )
+}
+
+export { Input }