Add a search box, matching NPS's Park Tiles viewer

Top-left map control (topmost, above Home/zoom) with a text input:
"lat, lng" is parsed and jumped to directly (same plain-text shape the
topbar's coordinate readout already copies to the clipboard), anything
else is geocoded via Nominatim — OSM's own geocoder, free, no API key,
matching the online basemap's own OSM-derived style. Online only, same
story as this app's other non-basemap online features (Radar, the
Wikipedia layer) — no offline geocoding index to fall back to.

public/css/style.css

@@ -879,6 +879,72 @@ html, body {
   color: #333;
 }
 
+.search-ctrl {
+  position: relative;
+}
+
+.search-ctrl__button svg {
+  display: block;
+  margin: 0 auto;
+  width: 18px;
+  height: 18px;
+}
+
+.search-ctrl__button.active {
+  background: #dbe9ff;
+}
+
+.search-panel {
+  position: absolute;
+  top: 0;
+  left: 100%;
+  margin-left: 8px;
+  z-index: 20;
+  width: 240px;
+  background: #fff;
+  border: 1px solid #ddd;
+  border-radius: 6px;
+  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.15);
+  padding: 6px 8px;
+  font-size: 13px;
+}
+
+.search-panel[hidden] {
+  display: none;
+}
+
+.search-panel__input {
+  width: 100%;
+  box-sizing: border-box;
+  border: 1px solid #ccc;
+  border-radius: 4px;
+  padding: 5px 7px;
+  font: inherit;
+}
+
+.search-panel__results {
+  list-style: none;
+  margin: 6px 0 0;
+  padding: 0;
+  max-height: 220px;
+  overflow-y: auto;
+}
+
+.search-panel__result {
+  padding: 6px 4px;
+  border-radius: 4px;
+  cursor: pointer;
+}
+
+.search-panel__result:hover {
+  background: #f0f0f0;
+}
+
+.search-panel__status {
+  padding: 6px 4px;
+  color: #888;
+}
+
 .notes-ctrl {
   position: relative;
 }