3D: add SpotLight object with nearest-lights performance guardrails

[Carrotstudio0]

Summary

This PR introduces a dedicated 3D SpotLight object (instead of a layer effect), with built-in performance guardrails that keep only the nearest spot lights active per layer.

What’s included

New object

• Added Scene3D::SpotLightObject as a real object visible in the scene editor.
• Object properties include:
  • Light: enabled, color, intensity, distance, cone angle, penumbra, decay
  • Shadows: castShadow, shadowQuality, shadowBias, shadowNormalBias, shadowRadius, shadowNear, shadowFar
  • Performance: per-light guardrailsEnabled

Guardrails system

• Added scene-level nearest-lights management in runtime:
  • By default, only the nearest 8 spot lights per layer are active.
  • Configurable per layer using:
    • Action: SetMaxActiveSpotLights(layer, max)
    • Expression: MaxActiveSpotLights(layer)
• Guardrails are evaluated each frame and applied deterministically using distance to camera.

Editor integration

• Added 2D and 3D scene editor renderers for SpotLightObject.
• Added default object editor configuration for this object.
• Added default object naming support (New3DSpotLight).
• Updated 3D model editor light detection to also consider Scene3D::SpotLightObject.

Files changed

• Extensions/3D/SpotLightRuntimeObject.ts (new)
• Extensions/3D/JsExtension.js
• newIDE/app/src/ObjectEditor/Editors/Model3DEditor.js
• newIDE/app/src/ObjectsList/index.js

Notes

• This PR focuses only on Spotlight-as-object architecture + guardrails.
• It is intentionally scoped to remain reviewable and independent from other 3D/post-processing changes.