fix(menu): Fix UX issues in USB-Mode

Add a short delay after opening USB-Mode to prevent immediate exit which
happened when pressing the select-button for a very short time.

Also exit the menu-app after exiting USB-Mode to force a reload and thus
immediately display changes in the apps/ folder.

Signed-off-by: Rahix <rahix@rahix.de>

preload/menu.py

@@ -67,16 +67,21 @@ def usb_mode(disp):
     disp.print("open", posx=52, posy=40, fg=color.CAMPGREEN_DARK)
     disp.update()
 
+    utime.sleep_ms(200)
+
     # Wait for select button to be released
-    while buttons.read(0xFF) == buttons.TOP_RIGHT:
+    while buttons.read() == buttons.TOP_RIGHT:
         pass
 
     # Wait for any button to be pressed and disable USB storage again
-    while buttons.read(0xFF) == 0:
+    while buttons.read() == 0:
         pass
 
     os.usbconfig(os.USB_SERIAL)
 
+    # Exit after USB-Mode to reload menu
+    os.exit(0)
+
 
 class MainMenu(simple_menu.Menu):
     timeout = 30.0