c5da79f8fc
The auto-sign panel earned its keep: in aura it signed ~20 specs autonomously and discriminates (several recent specs escalated to the human path). The needless complexity was the configuration freedom around it — spec_auto_sign was a per-project toggle that was only ever meant to be on. Remove the toggle. Auto-sign is now fixed /boss behaviour, with the human sign-off pause as the escalation target (objective gate red / design BLOCK / INFRA_ERROR / budget spent). The panel itself, the Step-1.5 seeding machinery, grounding-check, and the spec-skeptic agent are unchanged; conventions.md can now state there is no per-project behavioural toggle at all.