ref(backend): verify ticket endpoint

[aldy505]

Notes for frontend @zuramai:

Endpoint: POST /scan-tiket Request body:

{
  "code": "string from qrcode"
}

Responses:

• Status code 400 (bad request) -- means either invalid request body or validation error (empty string for "code" field)
• Status code 406 (not acceptable) -- means invalid ticket
• Status code 500 (internal server error) Every of these errors has the response body shape of:

  {
    "message": "Friendly text",
    "errors": "Not so friendly text",
    "request_id": "Some text to trace back to Sentry"
  } 

• Status code 200 (ok) -- ticket is verified with response body of:

  {
    "message": "Ticket confirmed",
    "student": false,
    "email": "johndoe@example.com"
  }

[zuramai]

I think we need "name" field returned as well

[aldy505]

I think we need "name" field returned as well

@zuramai done