Comparison-page UI for two side-by-side PTI maps
mod_pti_comparepage_ui.RdReturns a two-column [shiny::fluidRow()] in which each column hosts a [mod_map_pti_leaf_ui()] container, allowing the user to compare two weighting schemes (or admin-level renderings) on adjacent maps. Each map gets its own namespace (`first_leaf` / `second_leaf`) so the two instances are addressable independently from the server side.