Fix group visibility not updating in viewport after undo/redo (#3335)

[phatgolo]

Fix group visibility not updating in viewport after undo/redo (#3335)

Problem

When toggling group visibility in the outliner after an undo/redo cycle, elements inside the group remain invisible in the 3D viewport even though the outliner shows them as visible.

Two issues contribute to this:

1. Canvas.updateVisibility() only updates element mesh visibility — it never syncs group mesh visibility, so toggling a group's eye icon doesn't propagate to the 3D scene.
2. The outliner drag-toggle's undo handler (Undo.initEdit) used a separate affected_groups array that only tracked directly targeted groups, missing any child groups toggled via forEachChild. This caused undo/redo to leave group visibility state inconsistent.

Changes

• canvas.js: Update group mesh visibility in Canvas.updateVisibility() to match each group's visibility property.
• outliner.js: Replace the incomplete affected_groups tracking with affected.filter(node => node instanceof Group), which correctly captures all affected groups including children. Remove the now-unused affected_groups variable.

Fixes #3335

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[juan3178316]

Yeah 🥳