Add support for custom raycaster intersection classes

[MakingSpiderSense]

Add support for custom raycaster intersection classes, rather than using the “interactable” class. Use data-holdable-intersection-class="your-class" on <a-scene> to set a custom class.

https://trello.com/c/B3O8ZNKt

[Copilot]

Pull Request Overview

Adds support for a customizable raycaster intersection class for the holdable component and standardizes the grab-position attribute name.

• Documentation updated to describe custom intersection class and new scene-level attribute.
• Logic added to read data-holdable-intersection-class from <a-scene> and apply it to entities.
• Renamed scene grab-position attribute from data-grab-position to data-holdable-grab-position.

Comments suppressed due to low confidence (4)

src/components/holdable/holdable.js:11

• [nitpick] The prefix "Rare:" is nonstandard and may confuse readers. Consider replacing it with "Note:" or aligning it with the existing list labels for clarity.

 * - Rare: If you want to use another class for raycaster intersections instead of "interactable", you can add it globally to the scene using `data-holdable-intersection-class="your-class"`. This will be used for all holdable objects unless overridden.

src/components/holdable/holdable.js:11

• The documentation mentions "unless overridden," but the code only reads the scene-level attribute. Either remove that phrase or implement per-entity override support to match the docs.

 * - Rare: If you want to use another class for raycaster intersections instead of "interactable", you can add it globally to the scene using `data-holdable-intersection-class="your-class"`. This will be used for all holdable objects unless overridden.

src/components/holdable/holdable.js:45

• Add unit tests to verify that the data-holdable-intersection-class attribute is correctly read from the scene and applied to entities.

        const sceneIntersectionClass = this.el.sceneEl.getAttribute("data-holdable-intersection-class");

src/components/holdable/holdable.js:45

• [nitpick] Consider also checking for a per-entity data-holdable-intersection-class attribute (e.g., this.el.getAttribute(...)) so users can override the intersection class on individual holdable objects.

        const sceneIntersectionClass = this.el.sceneEl.getAttribute("data-holdable-intersection-class");