実装メモ：Reality Composer Pro で定義したパーティクルを Reality View のエンティティにアタッチする

func attachParticleEffect(to entity: Entity) async throws {
    let particlesRoot = try await Entity(
        named: "ParticleEffect",
        in: realityKitContentBundle // already defined in Packages/RealityKitContent/Sources/RealityKitContent/RealityKitContent.swift
    )
    guard
        let emitterSourceEntity = particlesRoot.findEntity(named: "ParticleEmitter"),
        let emitterComponent = emitterSourceEntity.components[ParticleEmitterComponent.self]
    else {
        assertionFailure("Emitter entity or ParticleEmitterComponent not found")
        return
    }
    entity.components.set(emitterComponent)
}