Vendor Leaflet 1.9.4 (JS, CSS, marker images) and wire it into
the esbuild/Tailwind asset pipeline. Create MapLive with band
selector buttons, auto-refresh, and a colocated JS hook that
renders propagation scores as color-coded circle markers with a
legend. Stub Propagation context and BandConfig modules provide
the data interface for the scoring pipeline.
Add nav bar with links to Map, QSOs, and Submit pages.
