Add Patch Database (patch2) Setup & Updates page (#1818 part C) New user-facing page covering why config/patch2 is empty on a fresh download, in-app (WinForms Git Patch2) + manual (git clone / zip / reuse) setup, updating, the custom submodule_patch2_url remote, and empty-state troubleshooting. Linked from Home, Getting-Started, and Reporting-Bugs.