Context

When verify_completeness = true and verify_provider references a non-existent provider, PlanVerifier::verify() fails open silently (returns complete=true). The consecutive-failure counter logs ERROR after 3 failures, but misconfiguration is not detected upfront.

Fix

Resolve verify_provider at DagScheduler::new() time when verify_completeness=true. Return Err(OrchestrationError::InvalidConfig(...)) if the provider does not exist. Emit a SchedulerAction::VerificationDegraded event so TUI can display a warning.