test infra: JUnit5 unit tests on Android modules + Compose UI test wiring

Add an architecture.android.unit.test convention plugin that runs local unit
tests on the JUnit5 platform via useJUnitPlatform() (AndroidUnitTest extends
Gradle's Test) + the unit-test bundle. Deliberately NOT using the
de.mannodermaus plugin (targets AGP 8.x; we're on AGP 9). Add
junit-platform-launcher (Gradle 9 dropped the bundled launcher); set the
instrumentation runner; add a compose-ui-test bundle pinning espresso/runner to
current versions (transitive espresso 3.5.0 calls the removed
InputManager.getInstance() on API 34+). CI now runs ./gradlew test and compiles
the instrumented tests. Drop unused testing catalog entries.

build-logic/convention/build.gradle.kts

@@ -47,6 +47,10 @@ gradlePlugin {
             id = "architecture.domain.module"
             implementationClass = "com.example.architecture.convention.DomainModuleConventionPlugin"
         }
+        register("androidUnitTest") {
+            id = "architecture.android.unit.test"
+            implementationClass = "com.example.architecture.convention.AndroidUnitTestConventionPlugin"
+        }
         register("compose") {
             id = "architecture.compose"
             implementationClass = "com.example.architecture.convention.ComposeConventionPlugin"

build-logic/convention/src/main/kotlin/com/example/architecture/convention/AndroidLibraryConventionPlugin.kt

@@ -19,6 +19,9 @@ class AndroidLibraryConventionPlugin : Plugin<Project> {
 
             defaultConfig {
                 minSdk = MIN_SDK
+                // Used by instrumented (androidTest) tests, e.g. the Compose UI test in
+                // :feature:characters:presentation-compose. Harmless for modules without androidTest.
+                testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
             }
 
             compileOptions {

build-logic/convention/src/main/kotlin/com/example/architecture/convention/AndroidUnitTestConventionPlugin.kt

@@ -0,0 +1,32 @@
+package com.example.architecture.convention
+
+import org.gradle.api.Plugin
+import org.gradle.api.Project
+import org.gradle.api.tasks.testing.Test
+import org.gradle.kotlin.dsl.dependencies
+import org.gradle.kotlin.dsl.withType
+
+/**
+ * Runs an Android library module's local unit tests (`src/test`) on the **JUnit 5 platform** with the
+ * shared `unit-test` toolset (JUnit Jupiter, kotlinx-coroutines-test, Turbine, AssertK).
+ *
+ * Deliberately does NOT use the `de.mannodermaus.android-junit5` Gradle plugin: its 1.11.x line
+ * targets AGP 8.x and we build on AGP 9.0. It isn't needed for *local* unit tests anyway —
+ * `com.android.build.gradle.tasks.factory.AndroidUnitTest` extends Gradle's [Test] task, so calling
+ * `useJUnitPlatform()` on it is enough (this mirrors `DomainModuleConventionPlugin`, which does the
+ * same for pure-JVM modules).
+ */
+class AndroidUnitTestConventionPlugin : Plugin<Project> {
+    override fun apply(target: Project) = with(target) {
+        dependencies {
+            add("testImplementation", libs.findBundle("unit-test").get())
+            add("testRuntimeOnly", libs.findLibrary("junit-jupiter-engine").get())
+            // Gradle 9 dropped the bundled launcher; JUnit 5 won't start without it.
+            add("testRuntimeOnly", libs.findLibrary("junit-platform-launcher").get())
+        }
+
+        tasks.withType<Test>().configureEach {
+            useJUnitPlatform()
+        }
+    }
+}

build-logic/convention/src/main/kotlin/com/example/architecture/convention/DomainModuleConventionPlugin.kt

@@ -21,6 +21,8 @@ class DomainModuleConventionPlugin : Plugin<Project> {
             add("testImplementation", libs.findLibrary("junit-jupiter-api").get())
             add("testImplementation", libs.findLibrary("assertk").get())
             add("testRuntimeOnly", libs.findLibrary("junit-jupiter-engine").get())
+            // Gradle 9 dropped the bundled launcher; JUnit 5 won't start without it.
+            add("testRuntimeOnly", libs.findLibrary("junit-platform-launcher").get())
         }
 
         tasks.withType<Test>().configureEach {