Note UX polish: pin marker, icon picker, fix Save button color

- The clicked location now stays marked (a plain maplibre-gl Marker,
  removed on save/cancel/deactivate) while the note form is open —
  before, nothing on the map showed where the pending note would land.
- POI_ICONS gains a dozen more symbols (water, dump station, toilets,
  playground, viewpoint, swimming, fishing, climbing, hiking, …) via
  Object.assign after PARK4NIGHT_TAGS' own icon constants are declared
  (they're below POI_ICONS in the file, so the literal itself can't
  reference them directly) — reused as real marker-badge glyphs, not
  just PARK4NIGHT_TAGS' inline description-tag icons. NoteSaveForm
  gets a picker grid for these, shown only for a Point note (a
  Measure-drawn line/polygon has no one spot for a badge).
- Fixed: .notes-panel__save's blue background was losing to
  .notes-panel__actions button's gray — same class-vs-class+element
  specificity trap .gpx-panel__action[hidden] already has a comment
  about elsewhere in this file. The button was never actually blue.

Verified live (properly simulating a logged-in session this time, via
Page.addScriptToEvaluateOnNewDocument rather than a post-load DOM
poke, since NotesControl's mount decision happens once, synchronously,
at page load): marker appears and clears correctly, 19 icons + "none"
render and select, Save renders #1a5fb4. Full suite: 115 runs, 0
failures.

public/css/style.css

@@ -888,6 +888,48 @@ html, body {
   resize: vertical;
 }
 
+.notes-panel__icons {
+  display: grid;
+  grid-template-columns: repeat(6, 1fr);
+  gap: 2px;
+  margin: 2px 0;
+}
+
+/* Same "author display wins over the UA [hidden] rule" gotcha as
+   .gpx-panel__action[hidden] elsewhere in this file. */
+.notes-panel__icons[hidden] {
+  display: none;
+}
+
+.notes-panel__icon-option {
+  width: auto;
+  height: auto;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  padding: 3px;
+  border: 1px solid transparent;
+  border-radius: 4px;
+  background: none;
+  color: #555;
+  cursor: pointer;
+}
+
+.notes-panel__icon-option svg {
+  width: 16px;
+  height: 16px;
+}
+
+.notes-panel__icon-option:hover {
+  background: #f0f0f0;
+}
+
+.notes-panel__icon-option.active {
+  border-color: #1a5fb4;
+  color: #1a5fb4;
+  background: #dbe9ff;
+}
+
 .notes-panel__target,
 .notes-panel__new-name {
   width: 100%;
@@ -917,7 +959,11 @@ html, body {
   cursor: pointer;
 }
 
-.notes-panel__save {
+/* ".notes-panel__actions " prefix (not just ".notes-panel__save") to
+   outrank ".notes-panel__actions button" — same class-count-vs-class+
+   element specificity trap as elsewhere in this file; without it this
+   lost and the Save button just looked like a second Cancel button. */
+.notes-panel__actions .notes-panel__save {
   background: #1a5fb4;
   color: #fff;
 }