Type Alias RandomMode

How a random node draws its seed:

• perParticle: stable per particle slot. Same particle gets the same draw every frame (good for per-particle constants — random size, color hue).
• perFrame: stable per particle per frame. Re-draws each frame, varies per particle (good for stochastic forces, twinkle).
• perSpawn: only valid inside spawn-scope graphs (on_spawn events). Stable per spawn event using the cumulative spawn index.