Strengthen validation retries and checkpoint safety

internal/modules/dnd/validate/combatturns/shape/validator.go

@@ -100,5 +100,5 @@ func DecodeOptions(options map[string]any) (Options, error) {
 func validateOptions(options map[string]any) error { _, err := DecodeOptions(options); return err }
 
 func rejection(message string) contracts.ValidationResult {
-	return contracts.ValidationResult{Approved: false, ReasonCode: ReasonCode, Message: message}
+	return contracts.ValidationResult{Approved: false, ReasonCode: ReasonCode, Message: message, CorrectionGuidance: "Return a complete combat-turn list with every required field present, valid combatant names, and valid source references."}
 }