Swap the pin marker for a rounded-square badge

The National Park Service frames its own map symbols (the icons already
vendored in for POI categories) in a rounded square, not a pin — pairing a
pin shape with NPS-style pictograms looked like two mismatched icon
conventions. Switched the marker to a rounded square to match.

This also simplifies the placement code: a pin has to anchor at its tip, so
the category glyph on top needed an offset computed from the pin/glyph
geometry to land in the pin's head. A square has no tip — both the badge and
the glyph layer just center directly on the coordinate with no offset math
at all.

public/js/icons.js

@@ -58,14 +58,17 @@ export const ROUTE_ICON = `
   <path d="M6.5 7.5C10 11 8 13 12 13s2 5 6.5 5" stroke-dasharray="2 2.2"/>
 </svg>`;
 
-// Filled version of WAYPOINT_ICON's outline (same path, fill instead of
-// stroke) — used as the map marker for individual waypoints, tinted by
-// category color via icon-color (see gpx.js). A pin/teardrop shape rather
-// than a plain dot specifically so it doesn't blend in with a base map
-// style's own small circular POI icons; the tip (not the head center) is
-// the anchor point, the standard map-pin convention.
-export const MAP_PIN_ICON = `
-<svg viewBox="0 0 24 24"><path d="M12 21s7-7.58 7-12a7 7 0 0 0-14 0c0 4.42 7 12 7 12z" fill="currentColor"/></svg>`;
+// A rounded-square badge — used as the map marker for individual waypoints,
+// tinted by category color via icon-color (see gpx.js). Not a plain dot,
+// which blended in with a base map style's own small circular POI icons,
+// and not a pin/teardrop either — a rounded square is the National Park
+// Service's own convention for framing these exact category symbols
+// (POI_ICONS below), so pairing the two looks native rather than like two
+// mismatched icon styles. Centered on the coordinate (no tip to anchor at),
+// which also means the category glyph on top needs no offset — both layers
+// just share the same center anchor at [0, 0].
+export const MAP_MARKER_ICON = `
+<svg viewBox="0 0 24 24"><rect x="1" y="1" width="22" height="22" rx="5" fill="currentColor"/></svg>`;
 
 // POI category glyphs (park4night/OsmAnd exports), keyed by the OsmAnd icon
 // name a file's <osmand:icon> extension carries — a small curated set for