feat(billing): plan taxonomy reconciliation + Stripe sync + internal-tester allowlist (#164)

Co-authored-by: Michael Chihlas <michael@resolutionflow.com>
Co-committed-by: Michael Chihlas <michael@resolutionflow.com>

frontend/src/pages/admin/InviteCodesPage.tsx

@@ -12,8 +12,9 @@ import type { InviteCodeResponse, InviteCodeCreateRequest } from '@/types/admin'
 
 const PLAN_OPTIONS = [
   { value: 'free', label: 'Free' },
+  { value: 'starter', label: 'Starter' },
   { value: 'pro', label: 'Pro' },
-  { value: 'team', label: 'Team' },
+  { value: 'enterprise', label: 'Enterprise' },
 ] as const
 
 const planBadgeVariant = (plan: string): 'success' | 'destructive' | 'warning' | 'default' => {
@@ -33,7 +34,7 @@ export function InviteCodesPage() {
   // Form state
   const [email, setEmail] = useState('')
   const [expiresInDays, setExpiresInDays] = useState('')
-  const [assignedPlan, setAssignedPlan] = useState<'free' | 'pro' | 'team'>('free')
+  const [assignedPlan, setAssignedPlan] = useState<'free' | 'pro' | 'starter' | 'enterprise'>('free')
   const [trialDays, setTrialDays] = useState('')
   const [note, setNote] = useState('')
 
@@ -269,7 +270,7 @@ export function InviteCodesPage() {
               aria-label="Plan"
               value={assignedPlan}
               onChange={(e) => {
-                const plan = e.target.value as 'free' | 'pro' | 'team'
+                const plan = e.target.value as 'free' | 'pro' | 'starter' | 'enterprise'
                 setAssignedPlan(plan)
                 if (plan === 'free') setTrialDays('')
               }}