Resolve a cost-adjustment Amount$ <ident> slot. Tries a direct integer
parse first, then looks up ident on the host’s SVar table and routes
through the subset of Count$… patterns relevant for cost adjustment.
Mirrors Java AbilityUtils.calculateAmount(host, name, staticAbility)
for the static-ability path. Owned by svar/ so cost callers don’t
reimplement SVar walking.
Resolve a Count$ SVar expression that requires game state access.
Handles patterns like Count$Valid Forest.YouCtrl, Count$Converge,
Count$CardPower, etc.