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"