* feat(cli): forward feedback submissions to backend endpoint
* fix(cli): truncate feedback fields to backend caps + ack before forwarding
Addresses PR review (via):
- Truncate comment (2000) / cli_version (100) / env (500) to the backend DTO
caps before POSTing, so a pasted stack trace is forwarded truncated instead
of rejected with a 422 the best-effort path swallows silently.
- Print "Thanks for the feedback!" before the best-effort forward so the ack
isn't blocked behind the (bounded) network call.
* fix(cli): type feedback fetch mock