Scraped a rival's full catalog, with receipts

Two catches the raw data hid. First, the API was non-deterministic: it returned a random ~65% slice each pass while reporting a fixed total, so a normal scrape silently missed a third and still looked complete. I only caught it because the unique count drifted between runs; the fix was a saturation scraper that converged to the true 651. Second, the apparent market leader's traffic was ~86% synthetic. The data was right; the obvious read was wrong. Catching both was the whole value.