3046f0dd6e
Adds rulespec.yaml and envelope.yaml support for machine-readable invariant checking during plan completion. - Add invariants module with Rulespec, ActionEnvelope, and evaluation logic - Add Invariants section to system prompt with workflow instructions - Show rulespec/envelope file status in plan verification output - Rulespec written during planning (captures constraints from task) - Envelope written after implementation (documents what was built)