feat(android-nav3): Track navigation state transitions

Add the observer layer that turns Navigation 3 back stack changes into breadcrumbs, scope state, and navigation transactions. This is also the point where the module starts carrying generated BuildConfig version metadata and its first non-empty API snapshot.

Author: 0xadam-brown

sentry-android-navigation3/api/sentry-android-navigation3.api

@@ -0,0 +1,8 @@
+public final class io/sentry/compose/navigation3/BuildConfig {
+	public static final field BUILD_TYPE Ljava/lang/String;
+	public static final field DEBUG Z
+	public static final field LIBRARY_PACKAGE_NAME Ljava/lang/String;
+	public static final field VERSION_NAME Ljava/lang/String;
+	public fun <init> ()V
+}
+

sentry-android-navigation3/build.gradle.kts

@@ -16,6 +16,9 @@ android {
 
   defaultConfig {
     minSdk = libs.versions.minSdk.get().toInt()
+
+    // for AGP 4.1
+    buildConfigField("String", "VERSION_NAME", "\"${project.version}\"")
   }
 
   buildTypes {
@@ -32,6 +35,10 @@ android {
     compilerOptions.apiVersion = KotlinVersion.KOTLIN_1_9
   }
 
+  testOptions {
+    unitTests.isReturnDefaultValues = true
+  }
+
   lint {
     warningsAsErrors = true
     checkDependencies = true
@@ -40,6 +47,8 @@ android {
     checkReleaseBuilds = false
   }
 
+  buildFeatures { buildConfig = true }
+
   androidComponents.beforeVariants {
     it.enable = !Config.Android.shouldSkipDebugVariant(it.buildType)
   }