Set up project skeleton (milestone 1)

- Architecture and feature overview in docs/ARCHITECTURE.md
- Gradle 9.8 / AGP 9.4 / Kotlin 2.4 with version catalog and convention plugins
- Modules :app, :core:*, :device-profiles, :feature:* (placeholder screens)
- Flavors core (no INTERNET, enforced by a build check) and full
- Material You theme, navigation, expert mode and dry-run settings (DataStore)
- Pixel 8-10 device detection, unit tests, GPLv3 license, English README with Obtainium badge

Co-Authored-By: Claude Opus 5.5 <[email protected]>

core/testing/build.gradle.kts

@@ -0,0 +1,9 @@
+plugins {
+    alias(libs.plugins.pixelwall.jvm.library)
+}
+
+dependencies {
+    api(project(":core:domain"))
+    api(libs.junit)
+    api(libs.kotlinx.coroutines.test)
+}

core/testing/src/main/kotlin/org/pixelwall/core/testing/FakeUserPreferencesRepository.kt

@@ -0,0 +1,14 @@
+package org.pixelwall.core.testing
+
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.update
+import org.pixelwall.core.domain.UserPreferences
+import org.pixelwall.core.domain.UserPreferencesRepository
+
+class FakeUserPreferencesRepository(initial: UserPreferences = UserPreferences()) : UserPreferencesRepository {
+    private val state = MutableStateFlow(initial)
+    override val preferences: Flow<UserPreferences> = state
+    override suspend fun setExpertMode(enabled: Boolean) = state.update { it.copy(expertMode = enabled) }
+    override suspend fun setDryRun(enabled: Boolean) = state.update { it.copy(dryRun = enabled) }
+}

core/testing/src/main/kotlin/org/pixelwall/core/testing/MainDispatcherRule.kt

@@ -0,0 +1,18 @@
+package org.pixelwall.core.testing
+
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.test.TestDispatcher
+import kotlinx.coroutines.test.UnconfinedTestDispatcher
+import kotlinx.coroutines.test.resetMain
+import kotlinx.coroutines.test.setMain
+import org.junit.rules.TestWatcher
+import org.junit.runner.Description
+
+@OptIn(ExperimentalCoroutinesApi::class)
+class MainDispatcherRule(
+    val dispatcher: TestDispatcher = UnconfinedTestDispatcher(),
+) : TestWatcher() {
+    override fun starting(description: Description) = Dispatchers.setMain(dispatcher)
+    override fun finished(description: Description) = Dispatchers.resetMain()
+}