Fix keystone list not wiping between calc perform

`env.keystonesAdded` was no longer getting reset before we start merging keystone effects. The new `modLib.mergeKeystones` keeps that table on the environment, and `wipeEnv` does not clear it. After the first calculation pass the table is full; on the next pass (any time the build recalculates by toggling a flask, change a config option, etc.) the merge sees every keystone as “already added” and skips adding their modLists. So every keystone loses its effects after the first recalculation.

src/Modules/CalcPerform.lua

@@ -1035,6 +1035,7 @@ function calcs.perform(env, skipEHP)
 	local enemyDB = env.enemyDB
 
 	-- Merge keystone modifiers
+	env.keystonesAdded = { }
 	modLib.mergeKeystones(env, env.modDB)
 
 	-- Build minion skills