Side pots

Build side-pot ladders from per-player commitments, sum layer sizes, and compute chip EV per player when each layer has its own win-equity matrix.

Layer equities: each column (layer) must sum to 1 across players.

Export	Summary
sidePotLadderFromCommitments	Main + side layers from commitments.
layeredPotChipEvFromEquities	Chip EV per player from layer equities.
sidePotLayersTotalChips	Sum of potChips across layers.
sidePotLayerCount	Number of side-pot layers.
sidePotBreakevenCallEquity	Breakeven equity for hero side-pot layer.
layeredPotChipEvFromEquitiesWithRake	Layered chip EV with rake per pot.