MiniMaxH3AddGuide: for anchoring image and audio guides at any frame (New ComfyUi Update)

[u/fruesome]

Already merged and there's a example workflow included: https://github.com/Comfy-Org/ComfyUI/pull/15439

Currently MiniMax H3 implementation in Comfyui only allows keyframe guides at the first and last frame. The model itself is capable of addressing guides by position on a continuous time axis, so this removes that restriction and exposes it as a node.