fix(transport): disable UART ESP-NOW bridge by default

Require serial_enabled true in settings to open serial_port; default false in
set_defaults for Wi-Fi-only and dev machines.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/settings.py

@@ -57,6 +57,9 @@ class Settings(dict):
         # down (0 disables). Helps drivers that reconnect after seeing traffic on 8766.
         if 'wifi_driver_hello_interval_s' not in self:
             self['wifi_driver_hello_interval_s'] = 10.0
+        # UART to ESP32 ESP-NOW bridge; default off (Wi-Fi drivers need no serial).
+        if 'serial_enabled' not in self:
+            self['serial_enabled'] = False
 
     def save(self):
         try: