Propose brief edit

Propose new wording for a project's or a task's agent brief (notes_for_agent) WITHOUT writing it. Briefs are the human's standing instructions to you, one-way, so you can never write one — but when a task has been sent back for a reason the brief should have covered, you are the one who knows the line that is missing. Give tier ("project" or "task"), target_id (the project or task id), text (the WHOLE brief as you propose it — a full replacement, not a patch; include what should stay), a reason (what went wrong and how this wording prevents it — this is what the human decides on), and source_task_id for the rejected task that prompted it. Nothing changes until a person applies it on the Needs you screen, where they see current vs proposed. It records the brief as you saw it: if someone edits that brief before yours is read, applying is refused rather than overwriting them. One open proposal per brief. The workspace brief can't be proposed here — it reaches every project, a teammate's agents included; use ask_decision for that.