Withdraw your team from a tournament

Withdraws a team you lead from a tournament, setting its participant row to WITHDRAWN. Works from either PENDING (a pending application) or APPROVED (a confirmed entry); anything else answers 400 error_invalid_input because there is nothing to withdraw.

This is NOT a pure status flip - two side effects change state a client may be holding. The team's outbound free-agent offers are all expired, and every free agent it had picked up is released back to the pool and dropped from its tournament roster. Re-read GET /tournaments/{identifier}/me afterwards rather than patching a cached entry.

Authority is derived from the participant, not from the URL's tournament: you must be the captain, co-captain, or organization owner of the team that participant belongs to, and a participantId belonging to a team you do not lead answers 403. A participantId belonging to a different tournament answers 404 error_tournament_not_found, identically to one that does not exist.

The organizer's counterpart is POST /tournaments/{identifier}/participants/{participantId}/remove, which requires manager authority on the tournament. Requires the tournaments actor entry capability at read-write.