ReassignContextRequest

Request body for POST /api/contexts/{id}/reassign — transfer a context's ownership to
a team. Binding a context to a team is the single path to shared authorship (read-only
sharing stays share_context; writing into a context requires team ownership).

{
    "to_team_id": "126146a4-5626-41ec-ba07-974e2f2ed771"
}