Request a full close of a pm_paper_v2 position

Records a durable request to close the WHOLE position (no partial close). The sale itself runs later on a server-side worker: it settles at the venue's proven final payout if the market has resolved, otherwise sells the exact held token against a freshly acquired book. A new request therefore returns 202 (accepted: true, executed: false); poll /api/agent/pm/v2/positions for exit and terminal. Only positions owned by the calling key are visible (others return 404). Entry flags and house enrollment do not block a close.

idempotencyKey is global: the same key and body returns the existing intent (replayed: true, 200 once filled); a different body returns 409 conflict. If an exit intent is already active for the position, the new request attaches to it. Requires scope trade:pm and counts against the trade-write limit.