Set up and debug the FmgLib.MauiMarkup hot reload loop — IFmgLibHotReload, InitializeHotReload(), FmgLibContentPage, FmgLibHotReloadHandler options, RebuildAll, ReloadFailed, dotnet watch vs IDE channels, VS Code and Rider limits, and writing a reload-safe Build(). Use when UI edits don't appear in the running app, when state resets or handlers fire twice after an edit, or when configuring the dev loop for a C# markup MAUI project.
