Reframe case study: product opportunity focus, not methodology war
Add HPI pre-filter negative case study with verified data comparison
Remove remaining Chinese — Wiki is now pure English
Add 25 Sourcing Strategies page + Low Price Index to Exclusive Methodology; cross-link with Glossary, Home, Sidebar
Add Exclusive Methodology page — Hidden Profit Index and proprietary algorithms; cross-link with Amazon, Glossary, Methodology, Cross-Platform overviews