fix(l2): a dot per DM send, lists that notice every change, the LED lit only on TX

- A pending DM shows a dot per send, as on the L1. The thread is read from
  the SD archive, which a resend never updated: it does now, and the
  thread's signature and patch state count the attempt.
- Nearby redraws when a node goes live, changes type or the units change;
  the scan popup when a name or the remote SNR arrives.
- The user LED is active high: it was lit all the time and went dark
  while transmitting.
- Sim hooks "dm" and "send" for testing a DM thread.

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

examples/companion_radio/ui-lvgl/UITask.h

@@ -129,6 +129,8 @@ public:
   void setVectorMap(bool on);
   void simMapAt(const char* spec);      // Map tools > Live tiles
   void simCompose(const char* text);    // the open thread's field: this text, keyboard up
+  void simDm();                         // the first chat contact's thread
+  void simSend() { sendFromCompose(); } // the field, sent
   // Navigation map (NavMap.h)
   void navTargetsPopup();
   void navClosePopup();