chore(deps): update all libraries and Gradle to latest stable versions

Bump the version catalog, Gradle wrapper, and convention plugins to the
latest stable releases. Verified with `./gradlew assembleDebug test`
(BUILD SUCCESSFUL, 21 unit tests pass).

Toolchain:
- Gradle 9.1.0 -> 9.5.1
- AGP 9.0.1 -> 9.2.1
- Kotlin 2.3.20 -> 2.4.0

Libraries:
- androidx-core 1.18.0 -> 1.19.0, appcompat 1.7.0 -> 1.7.1,
  fragment 1.8.5 -> 1.8.9, navigation 2.9.0 -> 2.9.8
- compose-bom 2026.03.01 -> 2026.05.01, material 1.12.0 -> 1.14.0
- coroutines 1.10.2 -> 1.11.0, serialization 1.8.1 -> 1.11.0,
  collections-immutable 0.3.8 -> 0.5.0
- koin 4.1.0 -> 4.2.1, ktor 3.1.3 -> 3.5.0, coil 3.1.0 -> 3.5.0
- JUnit 5.11.4 -> 6.1.0, turbine 1.2.0 -> 1.2.1, mockk 1.14.3 -> 1.14.11

Required side-effect:
- compileSdk 36 -> 37 (mandated by androidx.core 1.19.0); targetSdk
  left at 36.

Also refresh stale JUnit 5 / AGP 9.0 / compileSdk 36 references in the
README and convention-plugin docs.

README.md

@@ -36,17 +36,17 @@ a small MVVM *About* screen for contrast, and a dedicated **error-handling demo*
 | Concern | Choice |
 |---|---|
 | Build | Multi-module Gradle + `:build-logic` **convention plugins**; a single **version catalog** (`gradle/libs.versions.toml`) is the only place versions live |
-| Toolchain | AGP 9.0.1, Kotlin 2.3.20, Gradle 9.1, `compileSdk`/`targetSdk` 36, `minSdk` 24, Java 17 |
+| Toolchain | AGP 9.2.1, Kotlin 2.4.0, Gradle 9.5.1, `compileSdk` 37 / `targetSdk` 36, `minSdk` 24, Java 17 |
 | UI | Jetpack Compose (Material 3) + one classic **Views/XML** renderer |
-| DI | Koin 4.1 (constructor DSL) |
+| DI | Koin 4.2 (constructor DSL) |
 | Networking | Ktor (OkHttp engine) + KotlinX Serialization |
 | Images | Coil 3 |
 | Navigation | type-safe Compose Navigation (`@Serializable` routes) |
 | Logging | Timber |
 | Async | Coroutines + Flow |
-| Testing | JUnit 5, MockK, Turbine, AssertK, `kotlinx-coroutines-test`, Ktor `MockEngine`, Compose UI test |
+| Testing | JUnit 6, MockK, Turbine, AssertK, `kotlinx-coroutines-test`, Ktor `MockEngine`, Compose UI test |
 
-> **AGP 9 gotcha:** AGP 9.0 has **built-in Kotlin**. Applying `com.android.application`/`library`
+> **AGP 9 gotcha:** AGP 9.2 has **built-in Kotlin**. Applying `com.android.application`/`library`
 > auto-applies the Kotlin Android plugin, so the convention plugins must **not** apply
 > `org.jetbrains.kotlin.android` themselves. Source lives in `src/main/kotlin`.
 
@@ -276,12 +276,12 @@ both resolve the **same** `CharacterListViewModel` class and supply its `SavedSt
 
 ## Testing
 
-Tests prove the architecture, not just the code. Stack: **JUnit 5**, **MockK**, **Turbine** (Flow),
+Tests prove the architecture, not just the code. Stack: **JUnit 6**, **MockK**, **Turbine** (Flow),
 **AssertK**, `kotlinx-coroutines-test`, Ktor **`MockEngine`**, and Compose UI test.
 
 | What | Where | Kind |
 |---|---|---|
-| `GetCharactersPageUseCase` | `:feature:characters:domain` `src/test` | pure JVM, JUnit 5 |
+| `GetCharactersPageUseCase` | `:feature:characters:domain` `src/test` | pure JVM, JUnit 6 |
 | `CharacterListViewModel`, `CharacterDetailViewModel` | `:feature:characters:presentation` `src/test` | JVM unit, MockK + Turbine + `SavedStateHandle` |
 | `NetworkCharacterRepository` | `:feature:characters:data` `src/test` | JVM unit, Ktor `MockEngine` |
 | `CharacterListScreen` (robot) | `:feature:characters:presentation-compose` `src/androidTest` | instrumented Compose UI |
@@ -301,7 +301,7 @@ Conventions demonstrated:
   reads as a scenario; it asserts a rendered item, the empty/error states, and that a tap fires the
   right `Action`.
 
-> **JUnit 5 on AGP 9:** the `de.mannodermaus.android-junit5` Gradle plugin targets AGP 8.x, so this
+> **JUnit 6 on AGP 9:** the `de.mannodermaus.android-junit5` Gradle plugin targets AGP 8.x, so this
 > repo doesn't use it. `AndroidUnitTest` extends Gradle's `Test`, so the `architecture.android.unit.test`
 > convention plugin just calls `useJUnitPlatform()` and adds the `unit-test` bundle - including the
 > `junit-platform-launcher`, which Gradle 9 no longer bundles.
@@ -323,7 +323,7 @@ possible but intentionally omitted (the VM logic is already covered by the share
 # Build
 ./gradlew assembleDebug                 # build the debug APK
 ./gradlew projects                      # print the module tree
-./gradlew test                          # all JVM unit tests (JUnit 5)
+./gradlew test                          # all JVM unit tests (JUnit 6)
 ./gradlew :feature:characters:presentation-compose:connectedDebugAndroidTest   # Compose UI test (needs a device)
 ```
 
@@ -339,7 +339,7 @@ android docs search "<topic>"           # search authoritative Android docs
 ```
 
 Requires JDK 17+ (the Gradle build pins a Java 17 toolchain) and the Android SDK
-(`compileSdk 36`, `minSdk 24`).
+(`compileSdk 37`, `minSdk 24`).
 
 ---
 

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

@@ -7,11 +7,11 @@ 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
+ * Runs an Android library module's local unit tests (`src/test`) on the **JUnit 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 -
+ * targets AGP 8.x and we build on AGP 9.2. 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).
@@ -21,7 +21,7 @@ class AndroidUnitTestConventionPlugin : Plugin<Project> {
         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.
+            // Gradle 9 dropped the bundled launcher; the JUnit Platform won't start without it.
             add("testRuntimeOnly", libs.findLibrary("junit-platform-launcher").get())
         }
 

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

@@ -8,7 +8,7 @@ import org.gradle.kotlin.dsl.withType
 
 /**
  * Pure-Kotlin (JVM) module for the domain layer: no Android dependencies. Adds Coroutines (for
- * `Flow`-returning repository interfaces) and runs unit tests on the JUnit 5 platform.
+ * `Flow`-returning repository interfaces) and runs unit tests on the JUnit Platform.
  */
 class DomainModuleConventionPlugin : Plugin<Project> {
     override fun apply(target: Project) = with(target) {
@@ -25,7 +25,7 @@ class DomainModuleConventionPlugin : Plugin<Project> {
             add("testImplementation", libs.findLibrary("mockk").get())
             add("testImplementation", libs.findLibrary("kotlinx-coroutines-test").get())
             add("testRuntimeOnly", libs.findLibrary("junit-jupiter-engine").get())
-            // Gradle 9 dropped the bundled launcher; JUnit 5 won't start without it.
+            // Gradle 9 dropped the bundled launcher; the JUnit Platform won't start without it.
             add("testRuntimeOnly", libs.findLibrary("junit-platform-launcher").get())
         }
 

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

@@ -7,7 +7,7 @@ import org.gradle.kotlin.dsl.configure
 import org.gradle.kotlin.dsl.getByType
 import org.jetbrains.kotlin.gradle.dsl.KotlinProjectExtension
 
-internal const val COMPILE_SDK = 36
+internal const val COMPILE_SDK = 37
 internal const val MIN_SDK = 24
 internal const val TARGET_SDK = 36
 internal const val JVM_TARGET = 17

feature/characters/domain/src/test/kotlin/com/example/architecture/feature/characters/domain/usecase/GetCharactersPageUseCaseTest.kt

@@ -18,7 +18,7 @@ import org.junit.jupiter.api.Test
 /**
  * Tests for the (thin pass-through) [GetCharactersPageUseCase]: it must forward the requested page to
  * the repository and return its result verbatim - success and error alike. Pure JVM test on the
- * JUnit 5 platform (see DomainModuleConventionPlugin); the [CharacterRepository] collaborator is a
+ * JUnit Platform (see DomainModuleConventionPlugin); the [CharacterRepository] collaborator is a
  * MockK mock, stubbed with `coEvery` and verified with `coVerify`.
  */
 class GetCharactersPageUseCaseTest {

gradle/libs.versions.toml

@@ -1,46 +1,46 @@
 [versions]
 # Build / language
-agp = "9.0.1"
-kotlin = "2.3.20"
+agp = "9.2.1"
+kotlin = "2.4.0"
 
 # AndroidX - core / lifecycle / activity / views
-androidxCore = "1.18.0"
+androidxCore = "1.19.0"
 androidxLifecycle = "2.10.0"
 androidxActivity = "1.13.0"
-androidxAppcompat = "1.7.0"
-androidxFragment = "1.8.5"
+androidxAppcompat = "1.7.1"
+androidxFragment = "1.8.9"
 androidxRecyclerview = "1.4.0"
-androidxNavigation = "2.9.0"
+androidxNavigation = "2.9.8"
 
 # Compose (BOM-managed)
-composeBom = "2026.03.01"
+composeBom = "2026.05.01"
 
 # Async / serialization
-coroutines = "1.10.2"
-kotlinxSerialization = "1.8.1"
-kotlinxCollectionsImmutable = "0.3.8"
+coroutines = "1.11.0"
+kotlinxSerialization = "1.11.0"
+kotlinxCollectionsImmutable = "0.5.0"
 
 # DI
-koin = "4.1.0"
+koin = "4.2.1"
 
 # Networking
-ktor = "3.1.3"
+ktor = "3.5.0"
 
 # Image loading
-coil = "3.1.0"
+coil = "3.5.0"
 
 # Logging
 timber = "5.0.1"
 
 # Material Components (Views renderer)
-material = "1.12.0"
+material = "1.14.0"
 
 # Testing
-junitJupiter = "5.11.4"
-junitPlatform = "1.11.4"
-turbine = "1.2.0"
+junitJupiter = "6.1.0"
+junitPlatform = "6.1.0"
+turbine = "1.2.1"
 assertk = "0.28.1"
-mockk = "1.14.3"
+mockk = "1.14.11"
 androidxTestExt = "1.3.0"
 androidxTestRunner = "1.7.0"
 androidxEspresso = "3.7.0"

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,6 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-9.1.0-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-9.5.1-bin.zip
 networkTimeout=10000
 validateDistributionUrl=true
 zipStoreBase=GRADLE_USER_HOME