fix: improve Bluetooth reliability

kernel/src/Drivers/USB/Bluetooth/Avrcp.hpp

@@ -10,10 +10,18 @@
 namespace Drivers::USB::Bluetooth::Avrcp {
 
     // Process an AVCTP packet arriving on an AVRCP control channel (PSM 0x0017).
-    // Implements a minimal AVRCP Target: unit/subunit info, pass-through accept,
-    // GetCapabilities, RegisterNotification (interim), absolute volume.  Runs
+    // Implements a minimal AVRCP Target: unit/subunit info, honest rejection of
+    // unimplemented pass-through controls, capabilities, one-shot absolute-
+    // volume notification, and absolute-volume control.  Runs
     // from the ACL receive path (DrainEvents, top-level) -- sending is safe
     // there, blocking waits are not (none are used).
     void ProcessAvctp(uint16_t localCid, const uint8_t* data, uint16_t len);
 
+    // Complete an outstanding EVENT_VOLUME_CHANGED registration.  AVRCP
+    // notifications are one-shot: after CHANGED the controller registers again.
+    void NotifyVolumeChanged(int percent);
+
+    // Drop registrations tied to a channel that L2CAP has torn down.
+    void OnChannelClosed(uint16_t localCid);
+
 }