9b2460633c
Implements validateWorkflow() that performs deep semantic checks on parsed WorkflowPayload before registration or execution: - Role reference integrity (unknown roles, orphans, reserved names) - Graph structure (/ constraints, reachability, edge targets) - Status-edge consistency (single/multi-exit matching) - Mustache template variable existence - oneOf discriminant validity ( const check) All errors collected (not fail-fast). Integrated into: - uwf workflow add (before CAS registration) - uwf thread start (local workflow materialization) Closes #506