Clean up hooks.h friend declarations for USB connection events

- Removed unnecessary Base class friend declaration
- Added conditional nRF52840 friend declaration only for nRF52 builds
- Uses ARDUINO_NRF52_ADAFRUIT define which is standard for Adafruit nRF52 boards

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: obra

src/kaleidoscope/hooks.h

@@ -69,9 +69,11 @@ class Hooks {
   friend class Runtime_;
   friend class plugin::FocusSerial;
   friend class plugin::LEDControl;
-  friend class driver::ble::BLEBluefruit;  // Allow BLEBluefruit to trigger hooks
+  friend class driver::ble::BLEBluefruit;  // Allow BLEBluefruit to trigger BLE connection hooks
+#ifdef ARDUINO_NRF52_ADAFRUIT
   template<typename _Props>
-  friend class driver::mcu::Base;  // Allow MCU drivers to trigger USB connection hooks
+  friend class driver::mcu::nRF52840;  // Allow nRF52840 to trigger USB connection hooks
+#endif
   friend void sketch_exploration::pluginsExploreSketch();
 
  private: