Add voxel grid downsampling button to Edit menu

[nabeya11]

Adds a GUI for the existing voxel_grid console command to the Edit menu, following the same "Grid input + button" pattern as "Create surface".
The button is labeled "Reduce points" so that the effect is clear for non-engineer users.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 39.34%. Comparing base (836d903) to head (8bcc2e4).

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #364   +/-   ##
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  Coverage   39.34%   39.34%           
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  Files           8        8           
  Lines        1426     1426           
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  Hits          561      561           
  Misses        829      829           
  Partials       36       36           

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[Copilot]

🟢 Approval recommended

The UI addition matches existing menu patterns and correctly invokes the existing voxel_grid command without introducing behavioral or structural issues.

Pull request overview

Adds a GUI entry in the Edit fold menu to trigger the existing voxel_grid console command, using the same “grid input + action button” pattern as “Create surface”, and labeling the action as “Reduce points” for clarity.

Changes:

• Adds a “Grid” numeric input (#voxelGridRes) for voxel grid resolution in the Edit menu.
• Adds a “Reduce points” button (#voxelGrid) wired to run voxel_grid <res> via pcdeditor.command(...).

File summaries

File	Description
pcdeditor.js	Adds Edit-menu UI (input + button) and click handler to run voxel_grid with the chosen resolution.

Review details

• Files reviewed: 1/1 changed files
• Comments generated: 0
• Review effort level: Lite

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[at-wat]

LGTM