[FE-37] NPS survey: frontend prompt and admin display

[yusuftomilola]

Overview

After a booking completes, surface the NPS survey in the dashboard so members can rate their experience without leaving the platform, and show aggregated NPS results in the admin analytics.

Context

• Dashboard page: frontend/app/dashboard/page.tsx
• Admin analytics page: frontend/app/admin/analytics/page.tsx
• Depends on BE-43 being implemented first

Tasks

• Add a useGetPendingNpsSurvey hook that checks if the current user has an unanswered NPS survey
• If pending: show a dismissible banner or modal on /dashboard — How was your experience at [Workspace Name]? Rate us 0–10
• NPS widget: 11 numbered buttons (0–10) with Not at all likely / Extremely likely labels; optional comment textarea below
• Submit calls POST /nps/respond; on success dismiss the prompt and show thank-you toast
• Dismiss for now hides the banner for 24 hours (store in localStorage)
• Admin analytics page: add an NPS summary card showing: NPS score (large number), promoter/passive/detractor % breakdown as a donut chart, last 5 recent comments

Files to Modify / Create

• frontend/app/dashboard/page.tsx
• frontend/app/admin/analytics/page.tsx
• New: frontend/components/nps/NpsBanner.tsx
• New: frontend/lib/react-query/hooks/nps/