Ticketing: automated CSAT survey emails on ticket solved

🔍 Problem Statement

As a support manager, I can't collect satisfaction feedback on solved tickets, which leaves us with no CSAT data after leaving Zendesk.

As a support admin, I want to enable an automatic CSAT survey email in the Email Center, so that customers are asked for feedback after their ticket is solved.
As a support manager, I want CSAT responses visible on the platform, so that I can review satisfaction per ticket and per agent without leaving Pelcro.

✔ Given CSAT is enabled in the Email Center, when a ticket has been Solved for 24 hours, then a survey email is sent to the ticket's customer.
✔ Given a Solved ticket, when it is reopened before the 24 hours elapse, then the scheduled survey is cancelled.
✔ Given a survey email, when the customer selects Good or Bad and optionally adds a comment, then the rating and comment are saved on the ticket.
✔ Given a ticket with a CSAT response, when an agent opens Ticket Details, then the rating, comment, and response date are displayed.
✔ Given the Tickets list, when an agent views or filters it, then a CSAT column shows each ticket's rating and the list can be filtered by rating.
✔ Given a ticket that already received a survey, when it is reopened and solved again, then no second survey is sent.
✔ Given a ticket with no customer email, or CSAT disabled in the Email Center, when the ticket is solved, then no survey is sent.
✔ This change will impact UI / API, specifically the Email Center CSAT template and toggle, the ticket status-change scheduler, a public survey-response endpoint, CSAT fields on the ticket resource, Ticket Details, and the Tickets list.
✔ This solution will include the following limitations: single survey template; binary Good/Bad rating; fixed 24-hour delay (not configurable); no aggregate CSAT dashboard or score trends in v1; survey link expiry.