feat: add reusable UI components for enhanced consistency

Introduce reusable UI components including `Button`, `Card`, `Accordion`, `DropdownMenu`, `HoverCard`, `Drawer`, `Avatar`, and others. Standardize styling and functionality across features to improve code maintainability and user experience.

frontend/src/components/ui/avatar.tsx

@@ -0,0 +1,53 @@
+"use client"
+
+import * as React from "react"
+import * as AvatarPrimitive from "@radix-ui/react-avatar"
+
+import { cn } from "@/lib/utils"
+
+function Avatar({
+  className,
+  ...props
+}: React.ComponentProps<typeof AvatarPrimitive.Root>) {
+  return (
+    <AvatarPrimitive.Root
+      data-slot="avatar"
+      className={cn(
+        "relative flex size-8 shrink-0 overflow-hidden rounded-full",
+        className
+      )}
+      {...props}
+    />
+  )
+}
+
+function AvatarImage({
+  className,
+  ...props
+}: React.ComponentProps<typeof AvatarPrimitive.Image>) {
+  return (
+    <AvatarPrimitive.Image
+      data-slot="avatar-image"
+      className={cn("aspect-square size-full", className)}
+      {...props}
+    />
+  )
+}
+
+function AvatarFallback({
+  className,
+  ...props
+}: React.ComponentProps<typeof AvatarPrimitive.Fallback>) {
+  return (
+    <AvatarPrimitive.Fallback
+      data-slot="avatar-fallback"
+      className={cn(
+        "bg-muted flex size-full items-center justify-center rounded-full",
+        className
+      )}
+      {...props}
+    />
+  )
+}
+
+export { Avatar, AvatarImage, AvatarFallback }