fix(server): make widget area gap optional

[mimoham24]

Overview

regarding the padding default value I did the following changes:

• padding object is nil if not set
• gap is declared as a pointer

[codecov]

Codecov Report

Merging #383 (f52b3f0) into main (a019c54) will not change coverage.
The diff coverage is 77.77%.

❗ Current head f52b3f0 differs from pull request most recent head 286dbd1. Consider uploading reports for the commit 286dbd1 to get more accurate results

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #383   +/-   ##
=======================================
  Coverage   35.58%   35.58%           
=======================================
  Files         346      346           
  Lines       30695    30695           
=======================================
  Hits        10922    10922           
  Misses      18716    18716           
  Partials     1057     1057           

Impacted Files	Coverage Δ
...ternal/adapter/gql/gqlmodel/convert_scene_align.go	9.73% <0.00%> (ø)
...ernal/infrastructure/mongo/mongodoc/scene_align.go	0.00% <ø> (ø)
server/internal/usecase/interactor/scene.go	0.00% <0.00%> (ø)
server/pkg/scene/builder/encoder.go	97.46% <ø> (ø)
server/pkg/scene/widget_area.go	92.72% <100.00%> (ø)
server/pkg/scene/widget_section.go	92.72% <100.00%> (ø)