feat(l1): drafts + tickets pages + coverage banner + seat counter widget

L1DraftsPage is a Phase 1 placeholder (AI drafts arrive in Phase 2).
L1TicketsPage replaces the stub with a status-filterable internal-tickets
queue. L1CoverageBanner renders inside L1RouteGuard so every /l1/* page
shows it for engineer-coverers (hidden for native L1). SeatCounterWidget
+ /api/seats.ts surface engineer + L1 seat usage from the /accounts/me/
seats endpoint (T9).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

frontend/src/pages/AccountSettingsPage.tsx

@@ -33,6 +33,7 @@ import { Spinner } from '@/components/common/Spinner'
 import { cn } from '@/lib/utils'
 import { usePermissions } from '@/hooks/usePermissions'
 import { useSubscription } from '@/hooks/useSubscription'
+import { SeatCounterWidget } from '@/components/admin/SeatCounterWidget'
 import { useAuthStore } from '@/store/authStore'
 import { CheckoutButton } from '@/components/subscription/CheckoutButton'
 import { toast } from '@/lib/toast'
@@ -432,6 +433,8 @@ export function AccountSettingsPage() {
           <section className="space-y-5 border-t border-border pt-8">
             <SectionLabel>People</SectionLabel>
 
+            <SeatCounterWidget />
+
             <form onSubmit={handleInvite} className="flex flex-wrap items-center gap-2">
               <input
                 type="email"