Invite a waitlist entry — generates invite code and sends email (admin only)

Request

• Base URL
  http://localhost:5000/api/v1
• Auth
  HTTP bearer
• TypeScript
  https://skmtc.dev/scrubbe/apis/scrubbe-api/docs/api/v1/waitlist/:id/invite/post.ts

  A function with typed inputs. Its response is checked against the schema.