run: critic can raise a run's step ceiling mid-flight (CriticHandle.MaxSteps)

Prerequisite for a full-fidelity mort agentcritic adapter (which adjusts a
healthy-but-long run's iteration budget, not just its deadline). executus's
CriticHandle was deadline+steer only; this adds the dynamic step ceiling above
an unchanged majordomo (which already exposes WithMaxStepsFunc).

- run.RunInfo += MaxIterations (the run's base ceiling, so a critic can raise it
  relative to the baseline).
- run.CriticHandle += MaxSteps() int — polled by the executor each step via
  agent.WithMaxStepsFunc; <=0 defers to the base. The executor uses
  WithMaxStepsFunc(critic.MaxSteps) when a critic is active, else WithMaxSteps.
- critic battery: handle.maxSteps (initialised from RunInfo.MaxIterations) +
  MaxSteps(); Decision gains RaiseStepsBy so an Escalator can raise the ceiling
  alongside ExtendBy. ExtendOnce default is unchanged (time-only).

Test: a critic returning MaxSteps=5 lets a base-MaxIterations=1 run complete two
tool-dispatch steps past the base ceiling. Core stays battery-free (run doesn't
import critic).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

run/executor.go

@@ -156,14 +156,15 @@ func (e *Executor) Run(ctx context.Context, ra RunnableAgent, inv tool.Invocatio
 	// Audit start (optional). The recorder satisfies RunTally; stamp it on the
 	// invocation so a self-status tool can read live progress.
 	info := RunInfo{
-		RunID:       inv.RunID,
-		SubjectID:   ra.ID,
-		Name:        ra.Name,
-		CallerID:    inv.CallerID,
-		ChannelID:   inv.ChannelID,
-		ParentRunID: inv.ParentRunID,
-		Inputs:      inv.SkillInputs,
-		StartedAt:   started,
+		RunID:         inv.RunID,
+		SubjectID:     ra.ID,
+		Name:          ra.Name,
+		CallerID:      inv.CallerID,
+		ChannelID:     inv.ChannelID,
+		ParentRunID:   inv.ParentRunID,
+		Inputs:        inv.SkillInputs,
+		StartedAt:     started,
+		MaxIterations: maxIter,
 	}
 	var rec RunRecorder
 	var stateAcc *RunStateAccessor
@@ -243,7 +244,10 @@ func (e *Executor) Run(ctx context.Context, ra RunnableAgent, inv tool.Invocatio
 
 	opts := []agent.Option{
 		agent.WithToolbox(toolbox),
-		agent.WithMaxSteps(maxIter),
+		// Step ceiling: a fixed WithMaxSteps(maxIter) normally, but when a critic is
+		// active it owns a DYNAMIC ceiling (WithMaxStepsFunc) so it can raise a
+		// healthy-but-long run's budget mid-flight. Falls back to maxIter.
+		critic.maxStepsOption(maxIter),
 		agent.WithToolErrorLimits(e.cfg.Defaults.MaxConsecutiveToolErrors, e.cfg.Defaults.MaxSameToolCallRepeats),
 		agent.WithStepObserver(stepObserver),
 	}