feat: add resend capability for platform and account invite codes

Revoke-and-recreate flow for both invite systems with email delivery
via Resend API. Includes account invite email template and audit logging.

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

frontend/src/pages/admin/InviteCodesPage.tsx

@@ -1,5 +1,5 @@
 import { useState, useEffect, useCallback } from 'react'
-import { Plus, Copy, Trash2, Ticket, Mail, MailCheck } from 'lucide-react'
+import { Plus, Copy, Trash2, Ticket, Mail, MailCheck, RefreshCw } from 'lucide-react'
 import { DataTable, PageHeader, StatusBadge, ActionMenu, EmptyState } from '@/components/admin'
 import type { Column } from '@/components/admin'
 import { Modal } from '@/components/common/Modal'
@@ -97,6 +97,16 @@ export function InviteCodesPage() {
     }
   }
 
+  const handleResend = async (code: string) => {
+    try {
+      const newInvite = await adminApi.resendInviteCode(code)
+      toast.success(`New code ${newInvite.code} sent to ${newInvite.email}`)
+      fetchCodes()
+    } catch {
+      toast.error('Failed to resend invite code')
+    }
+  }
+
   const inputClass = cn(
     'w-full rounded-md border border-white/10 bg-black/50 px-3 py-2 text-sm text-white',
     'placeholder:text-white/40 focus:outline-none focus:border-white/30 focus:ring-2 focus:ring-white/20'
@@ -183,6 +193,11 @@ export function InviteCodesPage() {
             icon: <Copy className="h-4 w-4" />,
             onClick: () => handleCopy(c.code),
           },
+          ...(c.is_valid && c.email ? [{
+            label: 'Resend',
+            icon: <RefreshCw className="h-4 w-4" />,
+            onClick: () => handleResend(c.code),
+          }] : []),
           ...(!c.is_used ? [{
             label: 'Delete',
             icon: <Trash2 className="h-4 w-4" />,