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>

settings.gradle.kts

@@ -0,0 +1,18 @@
+pluginManagement {
+    repositories {
+        google()
+        mavenCentral()
+        gradlePluginPortal()
+    }
+}
+
+dependencyResolutionManagement {
+    repositoriesMode.set(RepositoriesMode.FAIL_ON_PROJECT_REPOS)
+    repositories {
+        google()
+        mavenCentral()
+    }
+}
+
+rootProject.name = "ble-serial"
+include(":app")