Shades the visible map by whether each point is currently blocked from
the sun by surrounding terrain (shademap.app-style), computed fully
offline via the same Terrarium DEM tiles the Terrain shading layer
already renders, plus this session's sun-position math and Radar's
checkbox+expandable UI shape.
dem.js pulls elevation-at-a-point out on its own since TODO.adoc's
slope readout and solar calculator will need the same lookup.
Both used to be their own separate sidebar icons; neither has
anything to manage beyond on/off, same as Wikipedia already got its
own Overlays entry for. Terrain shading is a plain checkbox item now.
Radar keeps its scrub/forecast controls, but behind an explicit
expand (clicking its name), separate from the checkbox — checking it
on shouldn't force the details open, and expanding to scrub/check the
forecast shouldn't also flip the layer on.
Both controls now build their own <li> (RadarControl.mount(li),
HillshadeControl.mount(li) — the latter moved into overlays.js
entirely, it has no reason to live in map.js once it's not building
its own sidebar icon) rather than a whole sidebar-item + flyout the
way they used to.
Also gave each Overlays item a leading icon: Wikipedia and Terrain
shading reuse existing NPS pictograms (WIKI_ICON, and WILDERNESS_ICON
newly exported from icons.js's forest entry — NPS has no dedicated
mountain/terrain glyph, wilderness-22.svg is the closest honest
match). Radar's is hand-drawn (a rain cloud) since NPS's set has
nothing weather-related to reuse.
Wikipedia doesn't belong inside "Tracks & Points" — that panel is for
files you add/remove/reorder, while Wikipedia is a live layer with
nothing to manage, just on/off. Gave it its own sidebar panel
(#overlays-panel, same shell as LiveTrackPanelControl) instead, sized
to hold more such checklist-only layers later without a redesign.
Moved all the wiki layer logic out of GpxPanelControl into a new
OverlaysControl (public/js/overlays.js). svgToImageData/badgeImageId/
escapeHtml are now exported from gpx.js so it doesn't have to
reimplement them — the same three helpers a second overlay would also
need.
randy