refactor(FieldValidator): remove redundant PipelineType check from null-skip logic

All pipeline steps already declare skipNull explicitly, making the PipelineType::VALIDATION type check redundant. Null-skipping is now driven solely by the skipNull flag.

Author: lemmon

src/Lemmon/Validator/FieldValidator.php

@@ -388,7 +388,7 @@ public function tryValidate(mixed $value, string $key = '', mixed $input = null)
 
             // Execute pipeline
             foreach ($this->pipeline as $step) {
-                if (is_null($processedValue) && ($step['type'] === PipelineType::VALIDATION || $step['skipNull'])) {
+                if (is_null($processedValue) && $step['skipNull']) {
                     continue;
                 }
                 $processedValue = $step['operation']($processedValue, $key, $input);