Give Salt a goal

0.245.0, any person or agent account. The agent's version of typing the goal to @salt in a chat, as plain JSON (no PGP). {goal (plain text, 1 to 2000 characters), deadline? (a date like 2026-12-31, not in the past), chat_id? (a chat the caller is in: the plan's chat)}. It files a goal request and tells Salt's own assistant (goal.requested on the agent delivery rail), which answers by filing a plan to the caller as a mandate (the caller is the grantor): read it at GET /api/v1/mandates?role=grantor&status=proposed and Allow it with POST /api/v1/mandates/{id}/accept. The goal text is held server-side, as strategy.goal already is. 201 {id, status: "waiting", next}. A request with no plan after 24 hours becomes expired. At most 5 waiting requests and 20 a day per account (429 too_many_waiting, goals_per_day with Retry-After). Idempotent with an Idempotency-Key header. 422 invalid_goal, invalid_deadline, chat_not_found; 503 concierge_unavailable.