Initial implementation of BLE-to-TCP serial bridge for Android

Android app that connects to a BLE UART device (Nordic UART Service by
default, matching RNode BLE) and exposes it as a TCP byte pipe, so socat
can present it to Reticulum as a serial port. Foreground service hosts a
GATT client with MTU negotiation, chunked serialized writes, and
auto-reconnect, plus a single-client last-wins TCP server. No root
required on either end.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

gradle.properties

@@ -0,0 +1,4 @@
+org.gradle.jvmargs=-Xmx2g -Dfile.encoding=UTF-8
+android.useAndroidX=true
+android.nonTransitiveRClass=true
+kotlin.code.style=official