fix(event-display): replace rainbow selection shader with glow outline

[deveshbervar]

Fixes #839

What this does

Replaces the animated rainbow selection shader with a clean golden glow outline, addressing the visual concern raised in #839.

Changes

• Replaced SELECTION_FRAGMENT_SHADER rainbow animation with a solid golden pulse (vec3(1.0, 0.85, 0.3))
• Replaced HOVER_FRAGMENT_SHADER static blue with a pulsing blue (vec3(0.3, 0.7, 1.0))
• Removed unused RAINBOW_FUNCTION constant
• Changed edge detection threshold to 1 for both hover and selection — removes the wireframe appearance

What is preserved from #721

• Multi-object selection architecture
• EdgesGeometry rendering (more efficient than the old OutlinePass)
• Controls-based architecture
• Double-click orbit targeting
• Drag detection
• Programmatic selection API

Note

Local build has a pre-existing BrowserslistError: Unknown version 146 of chrome issue on this machine unrelated to these changes.

[deveshbervar]

Hi @EdwardMoyse, this PR addresses #839.

Rather than a full revert, I kept the multi-selection architecture and performance improvements from #721 but made the following changes to effects-manager.ts:

• Replaced the animated rainbow SELECTION_FRAGMENT_SHADER with a clean golden glow (vec3(1.0, 0.85, 0.3) with sine pulse)
• Replaced the static HOVER_FRAGMENT_SHADER with a pulsing blue (vec3(0.3, 0.7, 1.0))
• Removed the unused RAINBOW_FUNCTION constant
• Changed edge detection threshold to 1 for both hover and selection — this removes the wireframe appearance

All interaction improvements from #721 are preserved (multi-selection, drag detection, double-click orbit, programmatic API).

Please let me know if you'd prefer a different color scheme or a full revert instead — happy to adjust!