audit: dpMid discount/premium zone filter — how many OBs does it kill

[cfournel]

checkForMSSBefore() rejects bullish OBs above dpMid and bearish OBs below dpMid. Measure the count and test disabling it.

[cfournel]

Result: dpMid discount/premium filter has zero effect — disabling it gives identical 11T/PF 2.80/64% win. The check is dead code in practice: OBs that survive outer-swing detection already happen to be in the correct zone. Reverted, no code change.