feat:계약 필드 에디터에 텍스트 정렬(L/C/R) 설정 기능 추가

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/Http/Controllers/ESign/EsignApiController.php

@@ -593,6 +593,7 @@ public function configureFields(Request $request, int $id): JsonResponse
             'fields.*.field_label' => 'nullable|string|max:100',
             'fields.*.field_variable' => 'nullable|string|max:50',
             'fields.*.font_size' => 'nullable|integer|min:6|max:72',
+            'fields.*.text_align' => 'nullable|string|in:L,C,R',
             'fields.*.is_required' => 'nullable|boolean',
         ]);
 
@@ -616,6 +617,7 @@ public function configureFields(Request $request, int $id): JsonResponse
                 'field_label' => $field['field_label'] ?? null,
                 'field_variable' => $field['field_variable'] ?? null,
                 'font_size' => $field['font_size'] ?? null,
+                'text_align' => $field['text_align'] ?? 'L',
                 'is_required' => $field['is_required'] ?? true,
                 'sort_order' => $i,
             ]);