Narrow macOS sandbox entitlement to /dev/cu. and /dev/tty. only

The /dev/ prefix granted read/write to all device nodes. The app only
needs access to serial port devices (/dev/cu.* and /dev/tty.*) for USB
LoRa communication.

macos/Runner/DebugProfile.entitlements

@@ -14,9 +14,11 @@
 	<true/>
 	<key>com.apple.security.device.usb</key>
 	<true/>
+	<!-- USB serial ports (/dev/cu.* and /dev/tty.*) for LoRa device communication -->
 	<key>com.apple.security.temporary-exception.files.absolute-path.read-write</key>
 	<array>
-		<string>/dev/</string>
+		<string>/dev/cu.</string>
+		<string>/dev/tty.</string>
 	</array>
 	<key>com.apple.security.device.camera</key>
 	<true/>

macos/Runner/Release.entitlements

@@ -10,9 +10,11 @@
 	<true/>
 	<key>com.apple.security.device.usb</key>
 	<true/>
+	<!-- USB serial ports (/dev/cu.* and /dev/tty.*) for LoRa device communication -->
 	<key>com.apple.security.temporary-exception.files.absolute-path.read-write</key>
 	<array>
-		<string>/dev/</string>
+		<string>/dev/cu.</string>
+		<string>/dev/tty.</string>
 	</array>
 	<key>com.apple.security.device.camera</key>
 	<true/>