feat(ui): drop echo toasts for actions the screen already shows

L1: Counters reset, Trail reset, Contact added/deleted, Logged in (admin),
Logged out, Channel deleted, Share target / Bot channel / Bot room set,
PIN set/cleared, Preset saved/deleted, and Unpinned on the favourites grid.
L2: Channel deleted, Counters reset, Region/Preset/Scope/Waypoint deleted,
Target cleared, Trail cleared, Message history deleted, Contact added/deleted.
Failures and Unpinned where the item leaves the screen stay.

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

examples/companion_radio/ui-lvgl/UITask.cpp

@@ -3787,7 +3787,6 @@ void UITask::nodeAction(uint8_t action) {
       break;
     case NODE_ADD:
       if (the_mesh.addDiscoveredContact(e.pub_key, e.name, e.type)) {
-        showToast("Contact added");
         _screen = SCR_NEARBY;
         buildNearby();
       } else {
@@ -3826,7 +3825,6 @@ void UITask::nodeAction(uint8_t action) {
         break;
       }
       if (the_mesh.deleteContactByKey(e.pub_key)) {
-        showToast("Contact deleted");
         _screen = SCR_NEARBY;
         buildNearby();
       }