fix: polish lock screen sequence — hints update instantly, screen stays on, triple-Back blocked

- Turn display on at first Back+Enter press so hints are visible even when screen was dark
- Extend _lock_wake_until on every sequence step to prevent screen blanking mid-press
- Set _next_refresh=0 on every Enter press (not just on completion) for immediate hint redraw
- Add _lock_seq_used flag to suppress the Back CLICK that fires on release after unlock
- Block triple-Back (buzzer toggle) when screen is locked

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

examples/companion_radio/ui-new/UITask.cpp

@@ -1187,19 +1187,25 @@ void UITask::loop() {
   if (ev == BUTTON_EVENT_CLICK) {
     if (back_btn.isPressed()) {
       // Enter clicked while Back is held — lock/unlock sequence
+      if (_display && !_display->isOn()) {
+        _display->turnOn();  // turn on display so hints are visible
+      }
+      _lock_wake_until = millis() + 5000;  // keep display on during sequence
       if (millis() - _lock_seq_ms > 3000) _lock_seq_count = 0;  // timeout reset
       _lock_seq_count++;
       _lock_seq_ms = millis();
+      _next_refresh = 0;  // update hint immediately on each press
       if (_lock_seq_count >= 3) {
         _lock_seq_count = 0;
+        _lock_seq_used = true;  // suppress Back release click
         _locked = !_locked;
         if (_locked) {
           _lock_wake_until = millis() + 2000;
         } else {
+          if (_display && !_display->isOn()) _display->turnOn();
           uint32_t aoff = autoOffMillis();
           if (aoff > 0) _auto_off = millis() + aoff;
         }
-        _next_refresh = 0;
       }
       // eat the Enter — don't pass to curr
     } else {
@@ -1232,14 +1238,15 @@ void UITask::loop() {
   }
   ev = back_btn.check();
   if (ev == BUTTON_EVENT_CLICK) {
-    if (_lock_seq_count > 0) {
+    if (_lock_seq_count > 0 || _lock_seq_used) {
-      // Back released mid-sequence — cancel sequence, eat the click
+      // Back released mid-sequence or after completing it — cancel/suppress
       _lock_seq_count = 0;
+      _lock_seq_used = false;
     } else {
       c = checkDisplayOn(KEY_CANCEL);
     }
   } else if (ev == BUTTON_EVENT_TRIPLE_CLICK) {
-    c = handleTripleClick(KEY_SELECT);
+    if (!_locked) c = handleTripleClick(KEY_SELECT);
   }
 #elif defined(PIN_USER_BTN)
   int ev = user_btn.check();

examples/companion_radio/ui-new/UITask.h

@@ -37,6 +37,7 @@ class UITask : public AbstractUITask {
   unsigned long _lock_wake_until;  // when to blank screen again after locked wake (5s)
   int  _lock_seq_count;            // Enter presses while Back held (lock/unlock sequence)
   unsigned long _lock_seq_ms;      // millis() of last lock-sequence press (for timeout)
+  bool _lock_seq_used;             // true = suppress next back_btn CLICK (post-sequence release)
   char _alert[80];
   char _notif_mel_buf[220];  // persistent RTTTL buffer for custom notification melodies
   unsigned long _alert_expiry;
@@ -92,7 +93,7 @@ public:
     _msgcount = _room_unread = 0;
     _locked = false;
     _lock_wake_until = 0;
-    _lock_seq_count = 0; _lock_seq_ms = 0;
+    _lock_seq_count = 0; _lock_seq_ms = 0; _lock_seq_used = false;
     _last_notif_ch_idx = -1;
     _last_notif_dm_valid = false;
     memset(_last_notif_dm_prefix, 0, sizeof(_last_notif_dm_prefix));