feat:E-Sign 필드 에디터에 폰트 크기 속성 추가

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

app/Models/ESign/EsignSignField.php

@@ -20,6 +20,7 @@ class EsignSignField extends Model
         'height',
         'field_type',
         'field_label',
+        'font_size',
         'field_value',
         'is_required',
         'sort_order',
@@ -31,6 +32,7 @@ class EsignSignField extends Model
         'position_y' => 'decimal:4',
         'width' => 'decimal:4',
         'height' => 'decimal:4',
+        'font_size' => 'integer',
         'is_required' => 'boolean',
         'sort_order' => 'integer',
     ];