Initial commit: Android Tether API app

Exposes phone connection status via HTTP API for tethered devices.

Features:
- Auto-start/stop server when tethering is enabled/disabled
- REST API with /status and /health endpoints
- Connection type, signal strength, carrier, battery info
- Foreground service with persistent notification

Stack: Kotlin 2.3, AGP 8.13, Gradle 8.13, compileSdk 36

app/build.gradle.kts

@@ -0,0 +1,61 @@
+plugins {
+    id("com.android.application")
+    id("org.jetbrains.kotlin.android")
+}
+
+android {
+    namespace = "dev.itsh.tetherapi"
+    compileSdk = 36
+
+    defaultConfig {
+        applicationId = "dev.itsh.tetherapi"
+        minSdk = 26
+        targetSdk = 36
+        versionCode = 1
+        versionName = "1.0.0"
+    }
+
+    buildTypes {
+        release {
+            isMinifyEnabled = false
+            proguardFiles(
+                getDefaultProguardFile("proguard-android-optimize.txt"),
+                "proguard-rules.pro"
+            )
+        }
+    }
+
+    compileOptions {
+        sourceCompatibility = JavaVersion.VERSION_21
+        targetCompatibility = JavaVersion.VERSION_21
+    }
+
+    buildFeatures {
+        viewBinding = true
+    }
+}
+
+kotlin {
+    compilerOptions {
+        jvmTarget.set(org.jetbrains.kotlin.gradle.dsl.JvmTarget.JVM_21)
+    }
+}
+
+dependencies {
+    implementation("androidx.core:core-ktx:1.17.0")
+    implementation("androidx.appcompat:appcompat:1.7.0")
+    implementation("com.google.android.material:material:1.12.0")
+    implementation("androidx.constraintlayout:constraintlayout:2.2.1")
+
+    // NanoHTTPD for lightweight HTTP server
+    implementation("org.nanohttpd:nanohttpd:2.3.1")
+
+    // Kotlin coroutines
+    implementation("org.jetbrains.kotlinx:kotlinx-coroutines-android:1.9.0")
+
+    // JSON serialization
+    implementation("com.google.code.gson:gson:2.11.0")
+
+    // Preferences for settings
+    implementation("androidx.preference:preference-ktx:1.2.1")
+}