feat: add Android target and default TreeNodeRow to tree-structure-compose (#39) (#48)

Add the `android` target to the Compose Multiplatform library and a sensible
default renderer, so the largest Compose audience is a first-class consumer.

- Core `tree-structure` and `tree-structure-compose` now build and publish an
  `-android` variant (compileSdk 35, minSdk 21). The core needs it too: its
  inline `tree { }` DSL is built per target, and Android consumers (JVM 11/17)
  cannot inline a JVM-21 build.
- `TreeNodeRow`: a foundation-only default node row (clickable, indented, with a
  `▾`/`▸` marker, no Material dependency), plus a no-content `LazyTree(root,
  label = …)` overload that uses it. The existing lambda overload is unchanged.
- New `samples` Android app module demonstrating `LazyTree` + `@Preview`
  (not published; excluded from API validation).
- Toolchain: Gradle wrapper 8.5 -> 8.10.2, Android Gradle Plugin 8.7.2.
- binary-compatibility-validator now emits per-target dumps (api/jvm, api/android)
  for the two multi-JVM-target modules; CI assembles the Android outputs.

tree-structure-compose/build.gradle.kts

@@ -2,6 +2,7 @@ import org.jetbrains.kotlin.gradle.ExperimentalWasmDsl
 
 plugins {
     alias(libs.plugins.kotlinMultiplatform)
+    alias(libs.plugins.androidLibrary)
     alias(libs.plugins.composeMultiplatform)
     alias(libs.plugins.composeCompiler)
     alias(libs.plugins.dokka)
@@ -68,6 +69,14 @@ kotlin {
 
     jvm()
 
+    androidTarget {
+        publishLibraryVariants("release")
+        // Match the Android variant's Kotlin bytecode to the Java level set in compileOptions.
+        compilerOptions {
+            jvmTarget.set(org.jetbrains.kotlin.gradle.dsl.JvmTarget.JVM_17)
+        }
+    }
+
     @OptIn(ExperimentalWasmDsl::class)
     wasmJs {
         browser()
@@ -85,3 +94,15 @@ kotlin {
         }
     }
 }
+
+android {
+    namespace = "com.github.adriankuta.datastructure.tree.compose"
+    compileSdk = libs.versions.androidCompileSdk.get().toInt()
+    defaultConfig {
+        minSdk = libs.versions.androidMinSdk.get().toInt()
+    }
+    compileOptions {
+        sourceCompatibility = JavaVersion.VERSION_17
+        targetCompatibility = JavaVersion.VERSION_17
+    }
+}