NoticeTextSections

The three user-controlled text sections a goal-state notice can embed.

Named rather than a bare tuple[str | None, str | None, str | None]: all five call sites unpack positionally and immediately re-pass the parts as keyword arguments to validate_goal_notice_text, where swapping two of them type-checks cleanly and would validate the wrong text against the wrong budget. Tuple unpacking still works, so the field names cost nothing.