[Feat] Pulse Admin Dashboard - manually grant plans to organizations

- Add admin layout with /api/admin/me check and access denial
- Add admin pages: dashboard, orgs list, org detail with grant form
- Add lib/api/admin.ts client for admin endpoints

Made-with: Cursor

app/admin/layout.tsx

@@ -0,0 +1,45 @@
+'use client'
+
+import { useEffect, useState } from 'react'
+import { useRouter } from 'next/navigation'
+import { getAdminMe } from '@/lib/api/admin'
+import { LoadingOverlay } from '@ciphera-net/ui'
+
+export default function AdminLayout({ children }: { children: React.ReactNode }) {
+  const [isAdmin, setIsAdmin] = useState<boolean | null>(null)
+  const router = useRouter()
+
+  useEffect(() => {
+    getAdminMe()
+      .then((res) => {
+        if (res.is_admin) {
+          setIsAdmin(true)
+        } else {
+          setIsAdmin(false)
+          // Redirect to home if not admin
+          router.push('/')
+        }
+      })
+      .catch(() => {
+        setIsAdmin(false)
+        router.push('/')
+      })
+  }, [router])
+
+  if (isAdmin === null) {
+    return <LoadingOverlay logoSrc="/pulse_icon_no_margins.png" title="Checking access..." />
+  }
+
+  if (!isAdmin) {
+    return null // Will redirect
+  }
+
+  return (
+    <div className="container mx-auto px-4 py-8">
+      <div className="mb-8 flex items-center justify-between">
+        <h1 className="text-2xl font-bold text-neutral-900 dark:text-white">Pulse Admin</h1>
+      </div>
+      {children}
+    </div>
+  )
+}