Strengthen validation retries and checkpoint safety

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

@@ -75,5 +75,5 @@ 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 spell-cast list with a nonblank spell name and caster plus valid source references for every cast."}
 }