feat(sdk-android): throwaway sample app for SDK validation

Single-activity Android app that calls Uatu.start() in
SampleApplication.onCreate and registers three extractors
(app_state, click_count, uptime_millis). MainActivity has a
button so click_count exercises non-trivial state.

sdk/android/sample/build.gradle.kts

@@ -0,0 +1,36 @@
+plugins {
+    id("com.android.application") version "8.11.0"
+    kotlin("android") version "2.1.21"
+}
+
+android {
+    namespace = "dev.uatu.sample"
+    compileSdk = 35
+
+    defaultConfig {
+        applicationId = "dev.uatu.sample"
+        minSdk = 24
+        targetSdk = 35
+        versionCode = 1
+        versionName = "0.0.1"
+    }
+
+    compileOptions {
+        sourceCompatibility = JavaVersion.VERSION_17
+        targetCompatibility = JavaVersion.VERSION_17
+    }
+
+    kotlinOptions {
+        jvmTarget = "17"
+    }
+
+    buildTypes {
+        debug {
+            isDebuggable = true
+        }
+    }
+}
+
+dependencies {
+    implementation(project(":sdk-android"))
+}