Add the Leaflet map page and client (markers, labels, layer toggles, shipment interpolation), the placement and authoring server actions, the map-features and map-import API routes, and the map styles including leaflet pane isolation so portals stack correctly.
Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)
Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>
