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/components/admin/SeatCounterWidget.tsx

@@ -0,0 +1,33 @@
+import { useEffect, useState } from 'react'
+import { seatsApi, type SeatUsage } from '@/api/seats'
+
+interface RowProps { label: string; check: SeatUsage['engineer'] }
+
+function SeatRow({ label, check }: RowProps) {
+  const overLimit = check.limit !== null && check.current > check.limit
+  const limitText = check.limit === null ? '∞' : check.limit
+  return (
+    <div className={overLimit ? 'text-warning' : ''}>
+      <p className="text-xs uppercase tracking-wider text-muted-foreground mb-1">{label}</p>
+      <p className="text-lg font-mono">{check.current} / {limitText}</p>
+      {overLimit && <p className="text-xs">Over limit (grandfathered)</p>}
+    </div>
+  )
+}
+
+export function SeatCounterWidget() {
+  const [usage, setUsage] = useState<SeatUsage | null>(null)
+
+  useEffect(() => {
+    seatsApi.getUsage().then(setUsage).catch(() => setUsage(null))
+  }, [])
+
+  if (!usage) return null
+
+  return (
+    <div className="rounded-lg border border-default bg-card p-4 grid grid-cols-2 gap-4">
+      <SeatRow label="Engineer seats" check={usage.engineer} />
+      <SeatRow label="L1 seats" check={usage.l1_tech} />
+    </div>
+  )
+}