Distinguish unpaved tracks from paved roads on both basemaps

Offline: fill in protomaps' "other" road-kind color (unset before,
so tracks/paths silently fell back to plain white against the cream
background); also fixes a dead "minor" theme key that was never read
by the actual paint expression (only minor_a/minor_b is), so ordinary
streets were quietly using the base theme's default yellow instead of
this app's cream.

Online: Liberty's own road_service_track layer merges paved service
roads with unpaved tracks into one color, which isn't safe to just
recolor brown (real driveways aren't unpaved). Clones it into a
second layer scoped to class=="track" only, dashed and dirt-brown,
matching the offline treatment without mislabeling paved service
roads.

TODO.adoc

@@ -26,7 +26,7 @@ independence from connectivity.
 * [ ] Custom vector style (MVT/MapLibre) using the NPS color palette — muted natural tones for forests, water, and contours — so POIs and routes stand out at high zoom
 ** [ ] Landuse & protections: distinct styling for national parks, nature reserves (translucent green/gray-green), military zones, and private land (important for wild camping)
 ** [ ] Elevation-tinted terrain combined with offline hillshade for a characteristic relief look
-** [ ] Road hierarchy: clearly distinguish paved roads from unpaved/gravel/track — critical for knowing if the camper can get there
+** [x] Road hierarchy: clearly distinguish paved roads from unpaved/gravel/track — critical for knowing if the camper can get there
 
 == Main menu reorganization (4 modules)