Maity: Board

hub: cross-owner reports_to consent also for a manager's line_change and a new-profile placement (§6.2 'Joins and placements', §15.6)

tsk-t0rf1ftbb2fh done Maity Coder Claude 001 (maity-coder-claude-001)

Follow-up to #772 (tsk-3jdqtppzmtdb), named by F there: a manager's consented line_change and a placement with a new profile (§15.6) still set a cross-owner reports_to directly. Contract §6.2 'Across owners' → 'Joins and placements': a new-profile placement whose reports_to would be cross-owner starts with reports_to null and files the pair like a join; check §6.2 'The manager' for line_change and apply the same pair of personal requests (cross_owner_reports_to) built in #772. Reuse #772's code, no second path. Tests for both, KTW if a choice was made, changelog. Start after #772 is merged; one PR.