Offline-Karten: Kern implementiert (Region-Download → IndexedDB → Offline-Render)

map-offline.js (window.MapOffline): lädt Vektorkacheln eines Bereichs via pmtiles.getZxy
in IndexedDB + cacht die Glyphs mit (KRITISCH: ohne Glyphs lässt MapLibre offline die
ganze Kachel fallen). byt://-Protokoll bedient MapLibre IndexedDB-first, remote-Fallback.
- map-gl-style.js: build({offline}) nutzt byt-Source statt pmtiles:// (Flag by_offline_tiles,
  Default AUS bis gerätegetestet); glyphs bleiben /fonts (SW-gecacht)
- ui.js + map.js: map-offline.js mitladen + byt-Protokoll registrieren
- getZxy liefert bereits dekomprimierte MVT (kein gunzip) → ~15 MB/5km in IndexedDB

Headless bewiesen: Download 97 Tiles (5km München) → Netz AUS → 1903 Features gerendert,
nicht geladene Gegend (Paris) korrekt leer. Offen: Download-Button/FAB-Segment-5-Verdrahtung,
adaptives Lernen, Bereichsauswahl/Routen-Korridor (siehe docs/OFFLINE_MAPS_PLAN.md).

backend/static/js/pages/map.js

@@ -678,16 +678,18 @@ window.Page_map = (() => {
       if ((src.includes('maplibre-gl.js') && window.maplibregl) ||
           (src.includes('pmtiles.js') && window.pmtiles) ||
           (src.includes('map-gl-style') && window.MapGLStyle) ||
+          (src.includes('map-offline') && window.MapOffline) ||
           (src.includes('map-gl-markers') && window.MapGLMarkers)) return res();
       const s = document.createElement('script');
       s.src = src + v; s.onload = res; s.onerror = rej;
       document.head.appendChild(s);
     })), Promise.resolve());
-    return seq(['/js/vendor/maplibre-gl.js', '/js/vendor/pmtiles.js', '/js/map-gl-style.js', '/js/map-gl-markers.js']).then(() => {
+    return seq(['/js/vendor/maplibre-gl.js', '/js/vendor/pmtiles.js', '/js/map-gl-style.js', '/js/map-offline.js', '/js/map-gl-markers.js']).then(() => {
       if (!(window.maplibregl && window.pmtiles && window.MapGLStyle && window.MapGLMarkers)) throw new Error('MapLibre nicht geladen');
       if (!_pmtilesProtoReg) {
         const proto = new pmtiles.Protocol();
         maplibregl.addProtocol('pmtiles', proto.tile);
+        try { window.MapOffline && MapOffline.registerProtocol(); } catch (e) {}
         _pmtilesProtoReg = true;
       }
       _maplibreLoaded = true;