Learned Lead Times

Min-n discipline (spec §7): a vendor needs ≥8 full receipts before its learned distribution replaces the default; learned vendors are shrunk toward the global distribution with weight n/(n+8). Drift flag fires after 3 consecutive receipts outside the expanding P10–P90 band on the same side, and auto-shifts the served estimate while raised. Raw quantiles are shown beside served values so an unserved raw median (e.g. a below-min-n vendor with one slow receipt) is never hidden.