[solo applicant] add a custom column while two jobs are being scored, both end up consistent

Walk the cross-cutting story scenarios that span pipeline + collaboration: three actors converging after an extract, adding a column mid-score, switching the view group mid-drag, friend-edits during a tailor, the agent-tailors-while-user-offline path, mid-tailor section adds, and the no-workspace-delete safety. These specs catch races that single-actor suites cannot see.

Proof set for Custom column added while two jobs are mid-score — both jobs re-score against new column once persisted