Phase 1 scaffold: auth for all apps

- Backend: Fastify with two listeners (public + internal), routes, services, DB migration + seed
- client_app: Flutter with BLoC, all auth screens (welcome, display name, register, OTP, force-register)
- mitra_app: Flutter with BLoC, OTP-only login
- control_center: React + Vite, email/password login, mitra/user management, anonymity settings
- Docs: phase1 plan, API contract, client app mockup
- CLAUDE.md and shared memory for all subprojects

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

control_center/src/pages/settings/SettingsPage.jsx

@@ -0,0 +1,45 @@
+import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query'
+import { apiClient } from '../../core/api/api-client'
+
+const fetchAnonymityConfig = async () => {
+  const res = await apiClient.get('/internal/config/anonymity')
+  return res.data.data
+}
+
+const updateAnonymityConfig = async (anonymity_enabled) => {
+  const res = await apiClient.patch('/internal/config/anonymity', { anonymity_enabled })
+  return res.data.data
+}
+
+export default function SettingsPage() {
+  const queryClient = useQueryClient()
+  const { data, isLoading } = useQuery({ queryKey: ['config-anonymity'], queryFn: fetchAnonymityConfig })
+
+  const mutation = useMutation({
+    mutationFn: updateAnonymityConfig,
+    onSuccess: () => queryClient.invalidateQueries({ queryKey: ['config-anonymity'] }),
+  })
+
+  if (isLoading) return <div>Loading...</div>
+
+  return (
+    <div>
+      <h1>Settings</h1>
+
+      <section style={{ marginBottom: 24 }}>
+        <h2>Anonymity</h2>
+        <p>Ketika dinonaktifkan, pengguna anonim akan diminta mendaftar setelah sesi selesai.</p>
+        <label style={{ display: 'flex', alignItems: 'center', gap: 8 }}>
+          <input
+            type="checkbox"
+            checked={data?.anonymity_enabled ?? true}
+            onChange={e => mutation.mutate(e.target.checked)}
+            disabled={mutation.isPending}
+          />
+          Izinkan pengguna anonim
+        </label>
+        {mutation.isError && <p style={{ color: 'red' }}>Gagal menyimpan.</p>}
+      </section>
+    </div>
+  )
+}