Move allauth + auth UI to legacy/

allauth/ (44 files) is a django-allauth React UI — a separate concern
from the Mizan protocol. Moved to legacy/ pending extraction into a
standalone mizan-django-allauth package.

Also moved to legacy/:
- client/AuthContext.tsx — generic auth state from /me endpoint
- client/RouterContext.tsx — framework-agnostic router adapter
- client/routing.tsx — UserRoute/StaffRoute/AnonymousRoute guards
- client/nextjs.tsx — Next.js router adapter for auth

These are auth UI infrastructure, not Mizan protocol. The Mizan core
only needs JWT for auth header selection (jwt/ stays — MizanProvider
depends on useJWT() to decide between Bearer and session auth).

Cleaned up re-exports in client/react.ts and vitest aliases.

33 React tests pass.

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

legacy/allauth/components/views/MFATOTPView.tsx

@@ -0,0 +1,51 @@
+'use client'
+
+import { useState } from 'react'
+import { useAllauthAPI } from '../../contexts/APIContext'
+import { AuthDjangoForm } from '../AuthDjangoForm'
+
+interface MFATOTPViewProps {
+    onSuccess?: () => void
+    onCancel?: () => void
+    onBack?: () => void
+    isReauth?: boolean
+}
+
+export function MFATOTPView({ onSuccess, onCancel, onBack, isReauth }: MFATOTPViewProps) {
+    const api = useAllauthAPI()
+    const [cancelling, setCancelling] = useState(false)
+
+    const handleCancel = async () => {
+        setCancelling(true)
+        try {
+            await api.session.logout()
+            onCancel?.()
+        } catch {
+            setCancelling(false)
+        }
+    }
+
+    // Build footer links
+    const footerLinks = []
+    if (onBack) {
+        footerLinks.push({ label: 'Use a different method', onClick: onBack })
+    }
+    if (onCancel) {
+        footerLinks.push({
+            label: cancelling ? 'Cancelling...' : 'Cancel',
+            onClick: handleCancel
+        })
+    }
+
+    const formName = isReauth ? 'mfa_reauthenticate' : 'mfa_authenticate'
+
+    return (
+        <AuthDjangoForm
+            formName={formName}
+            title="Authenticator App"
+            subtitle="Enter the 6-digit code from your authenticator app."
+            onSuccess={() => onSuccess?.()}
+            footerLinks={footerLinks}
+        />
+    )
+}