fix: reduce idle CPU wakeups and deferred-work polling

kernel/src/Drivers/USB/Bluetooth/Bluetooth.cpp

@@ -419,6 +419,14 @@ namespace Drivers::USB::Bluetooth {
     // ServiceEvents — steady-state event pump (idle loop)
     // =========================================================================
 
+    bool HasDeferredWork() {
+        if (g_initPending.load(std::memory_order_acquire) &&
+            !g_initialized && Fs::Vfs::IsDriveRegistered(0)) {
+            return true;
+        }
+        return g_initialized && Hci::HasPendingCommands();
+    }
+
     void ServiceEvents() {
         if (!g_initialized) return;
         if (Xhci::InPollContext()) return;   // never nest under PollEvents

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();

kernel/src/Drivers/USB/Bluetooth/Hci.cpp

@@ -1719,6 +1719,11 @@ namespace Drivers::USB::Bluetooth::Hci {
         s_active.store(false, std::memory_order_release);
     }
 
+    bool HasPendingCommands() {
+        return g_pendingTail.load(std::memory_order_acquire) !=
+               g_pendingHead.load(std::memory_order_acquire);
+    }
+
     bool WaitSecureSendResult(uint32_t timeoutMs, uint8_t* outResult, uint8_t* outStatus) {
         uint64_t start = Timekeeping::GetMilliseconds();
         while (Timekeeping::GetMilliseconds() - start < timeoutMs) {

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

@@ -331,6 +331,7 @@ namespace Drivers::USB::Bluetooth::Hci {
     // real confirmed transfers.  Call from top-level (e.g. the connect loop),
     // NOT from an event handler -- event handlers only enqueue.
     void ProcessPendingCommands();
+    bool HasPendingCommands();
 
     // ACL TX flow control: outstanding (un-acked) ACL packets, and the
     // controller's ACL buffer count (Number-Of-Completed-Packets credits).  The