Native MapLibre OpenMap (#2273)

Same test as the /preview/bbMap PoC — California (mls_id:ca45), real openmap/data from preview.mbb2.com — but running through the real <bb-widget> OpenMap widget instead of a standalone page. <mbb-map> is now native MapLibre — same tag the backend already emits, so this is a pure JS swap with no markup change.
Bundle: /src/my-buying-buddy.5.0.native.min.js — isolated from the shared development bundle.