fix(ui): don't draw the new-message alert over a full-screen keyboard

UITask::newMsg() (fired for every incoming DM/channel message) triggers a
3s "Msg: <sender>" overlay drawn on top of whatever screen is current --
including the shared KeyboardWidget when it's occupying the full screen
for text entry (message compose, room/repeater password, channel name,
device name, admin custom command, ...). A message arriving mid-typing
blanked out the letter grid for the full 3s with no way to see what was
being typed.

KeyboardWidget now tracks whether it was actually rendered this frame
(_visible, set at the top of render(), cleared by the new beginFrame()).
UITask's render loop calls _kb.beginFrame() before curr->render() and
skips the alert overlay when the keyboard turned out to be what got
drawn -- covers every screen that shares _kb, not just message compose.
The alert itself is unaffected (still fires, still expires after 3s) --
it just doesn't draw over the keyboard.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

examples/companion_radio/ui-new/KeyboardWidget.h

@@ -280,6 +280,15 @@ struct KeyboardWidget {
   // next letter, then reverts) — Hold-Enter on Shift toggles caps_lock, which
   // keeps it on for a whole run of capitals instead.
   bool caps_lock = false;
+  // Set by render() every time it's actually called; UITask clears it before
+  // curr->render() each frame (beginFrame()) so it reflects only "was the
+  // keyboard the thing on screen this frame" -- lets the alert overlay (new
+  // message toast) skip drawing over a full-screen keyboard, regardless of
+  // which screen (Messages/Bot/Settings/Admin/...) currently owns it.
+  bool _visible = false;
+  void beginFrame() { _visible = false; }
+  bool isVisible() const { return _visible; }
+
   char _ph_buf[KB_PH_MAX][KB_PH_LEN];
   int  _ph_count;
   PopupMenu _ph_menu;
@@ -438,6 +447,7 @@ struct KeyboardWidget {
   }
 
   int render(DisplayDriver& display) {
+    _visible = true;
     // A stale mid-cycle T9 press (no further input since) finalizes on its own —
     // the character is already committed to buf, this just stops a later Enter
     // on the same cell from being treated as a continued cycle.

examples/companion_radio/ui-new/UITask.cpp

@@ -2284,8 +2284,15 @@ void UITask::loop() {
       _next_refresh = millis() + Features::LOCKSCREEN_REFRESH_MS;
     } else if (!_locked && millis() >= _next_refresh && curr) {
       _display->startFrame();
+      _kb.beginFrame();
       int delay_millis = curr->render(*_display);
-      if (millis() < _alert_expiry) {  // alert overlay on top of any screen
+      // Skip the alert overlay (new-message toast) while the keyboard is the
+      // thing actually on screen this frame -- it's shared across Messages/
+      // Bot/Settings/Admin/etc., so this covers every screen that uses it for
+      // full-screen text entry, not just message compose. Otherwise a message
+      // arriving mid-typing blanks out the letter grid for 3s with no way to
+      // see what's being typed.
+      if (millis() < _alert_expiry && !_kb.isVisible()) {  // alert overlay on top of any (non-keyboard) screen
         renderAlertOverlay();
         // Keep refreshing the underlying screen at its own cadence (capped at the
         // alert's expiry) so layouts that settle over a frame — e.g. the message-