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]>

build-logic/convention/src/main/kotlin/ProjectExtensions.kt

@@ -0,0 +1,25 @@
+import org.gradle.api.JavaVersion
+import org.gradle.api.Project
+import org.gradle.api.artifacts.VersionCatalog
+import org.gradle.api.artifacts.VersionCatalogsExtension
+import org.gradle.kotlin.dsl.getByType
+import org.gradle.kotlin.dsl.withType
+import org.jetbrains.kotlin.gradle.dsl.JvmTarget
+import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
+
+internal val Project.libs: VersionCatalog
+    get() = extensions.getByType<VersionCatalogsExtension>().named("libs")
+
+internal fun VersionCatalog.lib(alias: String) = findLibrary(alias).get()
+
+internal fun VersionCatalog.int(alias: String) = findVersion(alias).get().requiredVersion.toInt()
+
+internal val JAVA_VERSION = JavaVersion.VERSION_17
+
+internal fun Project.configureKotlin() {
+    tasks.withType<KotlinCompile>().configureEach {
+        compilerOptions {
+            jvmTarget.set(JvmTarget.JVM_17)
+        }
+    }
+}