Format the structured lines in park4night waypoint popups

A park4night <desc> packs a free-text narrative and several lines of
structured data (address, rating, services, activities, the listing URL)
into one field, separated only by newlines. Rendered as a single paragraph
it read as a wall of run-together text — no visual hierarchy between the
actual description and what's really key-value metadata.

formatDescription now recognizes "Label: value" lines (Rating/Services/
Activities) and bare-URL lines, and gives each its own row instead of
burying them in the narrative paragraph: a bordered meta block with bold
labels, and an isolated link line. Anything that doesn't match — the real
narrative text, or a plain GPX file's <desc> with no such structure — stays
exactly as it rendered before, so this only adds structure, never removes
or reorders text.

public/css/style.css

@@ -450,6 +450,32 @@ html, body {
   letter-spacing: 0.02em;
 }
 
+.gpx-popup__description {
+  line-height: 1.4;
+}
+
+.gpx-popup__meta {
+  margin-top: 8px;
+  padding-top: 6px;
+  border-top: 1px solid #eee;
+  font-size: 12px;
+  line-height: 1.5;
+}
+
+.gpx-popup__meta-row + .gpx-popup__meta-row {
+  margin-top: 2px;
+}
+
+.gpx-popup__meta-label {
+  font-weight: 600;
+  margin-right: 4px;
+}
+
+.gpx-popup__link {
+  margin-top: 6px;
+  font-size: 12px;
+}
+
 .gnss-control__status {
   color: #888;
   white-space: nowrap;