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/settings.gradle.kts

@@ -0,0 +1,15 @@
+dependencyResolutionManagement {
+    repositories {
+        google()
+        mavenCentral()
+        gradlePluginPortal()
+    }
+    versionCatalogs {
+        create("libs") {
+            from(files("../gradle/libs.versions.toml"))
+        }
+    }
+}
+
+rootProject.name = "build-logic"
+include(":convention")