feat(tickets): add TicketsPage with URL-param filter state, stub detail panel and modal

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

frontend/src/components/tickets/TicketDetailPanel.tsx

@@ -0,0 +1,12 @@
+// Placeholder — full implementation in Task 16
+import type { PSATicketSearchResult } from '@/types/integrations'
+
+interface Props {
+  ticket: PSATicketSearchResult
+  onClose: () => void
+  onStatusUpdated?: (ticketId: number, newStatus: string) => void
+}
+
+export function TicketDetailPanel(_props: Props) {
+  return <div>Loading ticket details…</div>
+}