Add admin-core frontend (Port 3008)

Next.js admin frontend for Core with 3 categories
(Communication, Infrastructure, Development), 13 modules,
2 roles (developer, ops), and 11 API proxy routes.
Includes docker-compose service and nginx SSL config.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

admin-core/app/(admin)/layout.tsx

@@ -0,0 +1,54 @@
+'use client'
+
+import { useEffect, useState } from 'react'
+import { useRouter } from 'next/navigation'
+import { Sidebar } from '@/components/layout/Sidebar'
+import { Header } from '@/components/layout/Header'
+import { Breadcrumbs } from '@/components/common/Breadcrumbs'
+import { getStoredRole } from '@/lib/roles'
+
+export default function AdminLayout({
+  children,
+}: {
+  children: React.ReactNode
+}) {
+  const router = useRouter()
+  const [sidebarKey, setSidebarKey] = useState(0)
+  const [loading, setLoading] = useState(true)
+
+  useEffect(() => {
+    const role = getStoredRole()
+    if (!role) {
+      router.replace('/')
+    } else {
+      setLoading(false)
+    }
+  }, [router])
+
+  const handleRoleChange = () => {
+    setSidebarKey(prev => prev + 1)
+  }
+
+  if (loading) {
+    return (
+      <div className="min-h-screen bg-slate-50 flex items-center justify-center">
+        <div className="animate-spin rounded-full h-12 w-12 border-b-2 border-primary-600"></div>
+      </div>
+    )
+  }
+
+  return (
+    <div className="min-h-screen bg-slate-50 flex">
+      <Sidebar key={sidebarKey} onRoleChange={handleRoleChange} />
+
+      <div className="flex-1 ml-64 transition-all duration-300">
+        <Header />
+
+        <main className="p-6">
+          <Breadcrumbs />
+          {children}
+        </main>
+      </div>
+    </div>
+  )
+}