Restructure the map controls from MapLibre corner buttons into a left
sidebar of icons with flyouts/panels (radar, GPX, GNSS), matching
OsmAnd's layout more closely:
- Base map and GPX selection are now full-height side panels docked
next to the sidebar (not small dropdown flyouts or a right-docked
panel), opening/closing exclusively via a small shared event bus
(panels.js) so only one is ever open at a time.
- The GPX panel's upload/new-folder controls are now icon buttons in
the header instead of an always-visible dropzone and form; dragging
a GPX file onto the tree, a specific folder, or straight onto the
map itself all upload it.
- New: Maptool::GpsdClient (lib/maptool/gpsd_client.rb) streams live
GNSS fixes from a local gpsd daemon over Server-Sent Events
(/api/gnss/stream) to a marker on the map (public/js/gnss.js) — one
background gpsd connection shared by every browser tab.
- The online map style (public/js/osmand-style.js) is now styled to
resemble OsmAnd's own rendering, applied to both the online and
offline (PMTiles) styles.
Also adds a GeolocateControl (browser geolocation) next to the zoom
controls.
