Buzzer: add playForced(); fix per-channel force-on notification ignoring global mute

buzzer.play() was returning early when _is_quiet=true, so channels with
explicit notification=ON were silent even though the logic correctly set
play=true. playForced() bypasses the quiet check for these overrides.

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

src/helpers/ui/buzzer.h

@@ -20,7 +20,8 @@ class genericBuzzer
 {
     public:
         void begin();  // set up buzzer port
-        void play(const char *melody); // Generic play function
+        void play(const char *melody);
+        void playForced(const char *melody);  // play regardless of quiet state
         void loop();  // loop driven-nonblocking
         void startup();  // play startup sound
         void shutdown();  // play shutdown sound