Replace frontend prototype with stac-map

[spwoodcock]

• Info here: https://github.com/hotosm/openaerialmap?tab=readme-ov-file#frontend-parts
• We should probably use stac-map to outsource development to a community effort, instead of a single in-house effort.
• The uploader will be branded, while the map browser will be now (or perhaps minimally branded with colour / fonts, but no logo).