fix: reduce idle CPU wakeups and deferred-work polling

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

@@ -27,6 +27,11 @@ namespace Drivers::USB::Bluetooth {
     // (PollEvents/DrainEvents/ProcessPendingCommands all self-serialize).
     void ServiceEvents();
 
+    // True when boot-deferred initialization or queued HCI control work needs
+    // an idle-context service pass. USB receive events are signaled separately
+    // by xHCI and cause the dispatcher to service Bluetooth in the same pass.
+    bool HasDeferredWork();
+
     // Query adapter state
     bool IsInitialized();
     uint8_t GetSlotId();