feat: a node map and a calendar on ui-new, a banner switch on the L2

- Nearby › Map (ui-new): the positioned nodes and you on one view, scaled
  to fit, with north, a scale bar and the selected node's name and
  distance; Left / Right picks a node, Up / Down zooms on it, Enter opens it.
- Clock tools › Calendar (ui-new): the month with today and the alarm's
  days; a tight grid on small screens, Left / Right pages the months.
- L2 Settings: a Message banner switch (on / off) in place of ui-new's
  three-way alert setting.
- Simulator: sim_nodes() puts eight positioned contacts around Kraków.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

examples/companion_radio/ui-lvgl/UITask.h

@@ -90,6 +90,7 @@ public:
   void setBrightnessPct(uint8_t pct, bool save);
   void applyDisplayPrefs() override;
   void setSchemaValue(int idx, int v);
+  void setMsgBanner(bool on);   // Settings > Display > Message banner
   void showNearby();
   void showMap();                  // in its current mode
   void openMap(bool nav);          // the one map; false: from Nodes, with the nodes on it and Back to Nodes
@@ -376,6 +377,7 @@ private:
   void schemaExtras(int page);
   void showMapOptions(uint8_t section);
   void schemaRow(lv_obj_t* card, int idx);
+  void msgBannerRow(lv_obj_t* card);
   void buildKeyboardPage(lv_obj_t* body);
   void buildAboutPage(lv_obj_t* body);
   void buildAdminPick();