feat: add S2 GhostMaps live intel layer

Adds an "S2 GhostMaps" layer (Events group) that renders S2 Underground's
GhostMaps KMZ exports (Common Intelligence Picture, Kinetic 30d, Border
Crisis, Iran CIP/Kinetic, Yemen FLOT, latest incident drop).

- server/providers/ghostMaps.js: watcher polls the repo's git smart-HTTP
  ref advertisement (default every 15s, GHOSTMAPS_POLL_SECONDS), fetches
  the tree only on a new head, caches commit-pinned files by blob sha and
  pushes catalog updates to browsers over SSE (/api/ghostmaps/events).
- src/layers/ghostMaps: KML reader, ArcGIS popup-table parsing, per-product
  data sources, product chips, horizon-culled pins, report cards.
- Unit tests, QA gate (scripts/qa-ghostmaps.mjs), credits (CC BY-NC-SA 4.0),
  i18n, voice manifest, layer-state token 5.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/data/geoFileImport.js

@@ -1040,7 +1040,13 @@ export function detachImportedTime(dataSource) {
   return dataSource;
 }
 
-function parseXml(text, what) {
+/**
+ * Parse KML or GPX text with the namespace repairs Cesium applies.
+ * @param {string} text
+ * @param {string} what Format name for the error message.
+ * @returns {Document}
+ */
+export function parseXml(text, what) {
   // Match the namespace repairs Cesium applies to ordinary exported KML.
   if (what !== 'GPX')
     text = String(text).replace(/<kml\b[^>]*>/i, (root) => {
@@ -1073,7 +1079,8 @@ function parseXml(text, what) {
   return doc;
 }
 
-function decodeXml(bytes) {
+/** Decode XML bytes, honouring a UTF-16 byte-order mark. */
+export function decodeXml(bytes) {
   const encoding =
     bytes[0] === 0xff && bytes[1] === 0xfe
       ? 'utf-16le'