Snap to Lower-Layer Keys While Working on Animation Layers

🔍 Problem
When working on an upper layer, it is hard to see which frames have keys on lower layers.
You end up toggling layers on/off constantly, which hurts efficiency.
Keying on arbitrary frames also scatters keys after Collapse.

💡 Requested feature
Snap the time slider to lower-layer keyframes with shortcuts such as < >.
A snap option that uses keys from the layer below, not the current layer.

📝 Note
I have tried scripts that copy lower-layer keys up to the working layer via a button or hotkey.

🎯 Expected benefit
More stable layer workflows and fewer polishing mistakes