Inspector: Add hierarchy tab and styles for scene management

[sm-heard]

Implemented a Scene Hierarchy Inspector feature for three.js.

https://raw.githack.com/sm-heard/three.js/feature/inspector-scene-hierarchy/examples/index.html#webgpu_tsl_compute_attractors_particles

Files Created

examples/jsm/inspector/tabs/Hierarchy.js (new file, ~450 lines)

• Hierarchical tree view of the scene graph using existing List/Item components
• Click-to-select with row highlighting
• BoxHelper visualization for selected objects in 3D viewport
• Editable property panel with:
  • Position (X, Y, Z)
  • Rotation (X, Y, Z in degrees)
  • Scale (X, Y, Z)
  • Name (editable text)
  • Type (read-only)
  • Visible (checkbox)
• Real-time updates (throttled to 250ms)
• Two-way binding between panel inputs and object transforms

Files Modified

1. examples/jsm/inspector/Inspector.js
   - Added import for Hierarchy
   - Created and registered the new tab
   - Hooked into resolveFrame() to update hierarchy from scene renders
2. examples/jsm/inspector/ui/Style.js
   - Added .list-item-row.selected styling for selection highlighting
   - Added .hierarchy-property-panel styling for the property panel

[mrdoob]

Can you ask Claude to not include the builds in the PR?

[sm-heard]

Yes sir. My bad, I thought I had kept that build folder out.

[mrdoob]

Also revert the changes in‎ .gitignore please.
We'll probably have to add .claude and CLAUDE.md anyway, but better to leave that change out of this PR.

[sm-heard]

Yes sir. Will do.

[sunag]

I prefer to separate the Hierarchy from the Object and Material Properties. Besides being more flexible to have the two tabs like Unity has, for example, it wouldn't break the layout as it is in Transform division.

Example: Hierarchy in left, Inspector( for us Properties) in Right We're not going to consider the dock here.

--
The object or material properties should follow a similar pattern to what we saw in Parameters tabs using List.

Another thing about the Material PR, let's try to unify this into just one tab called Properties where, depending on the object selected, the related properties appear. In this sense, the Hierarchy should also show the materials and geometry of the meshes.