Add admin dashboard pages and restructure admin route

Introduces new admin dashboard pages for alerts, bans, invites, orders, settings, status, and vendors under app/dashboard/admin/. Moves the main admin page to the new dashboard structure and adds a shared admin layout. Updates sidebar configuration and adds supporting components and hooks for admin features.

hooks/useUser.ts

@@ -0,0 +1,50 @@
+"use client"
+
+import { useState, useEffect } from 'react'
+import { clientFetch } from '@/lib/api-client'
+
+interface Vendor {
+  _id: string;
+  username: string;
+  storeId: string;
+  pgpKey: string;
+  __v: number;
+}
+
+interface User {
+  vendor: Vendor;
+}
+
+export function useUser() {
+  const [user, setUser] = useState<User | null>(null)
+  const [loading, setLoading] = useState(true)
+  const [error, setError] = useState<string | null>(null)
+
+  useEffect(() => {
+    const fetchUser = async () => {
+      try {
+        setLoading(true)
+        const userData = await clientFetch<User>("/auth/me")
+        setUser(userData)
+        setError(null)
+      } catch (err) {
+        console.error("Failed to fetch user:", err)
+        setError("Failed to fetch user data")
+        setUser(null)
+      } finally {
+        setLoading(false)
+      }
+    }
+
+    fetchUser()
+  }, [])
+
+  const isAdmin = user?.vendor?.username === 'admin1'
+
+  return {
+    user,
+    loading,
+    error,
+    isAdmin
+  }
+}