chore: get Android project building (toolchain, deps, manifest, launcher icon)

- Fix dependency versions (Retrofit 2.11, OkHttp 4.12, Compose BOM)
- Add Material Components for the app theme
- Add --add-exports/--add-opens for kapt on JDK 21
- Remove deprecated manifest package attr; add INTERNET permission
- Add adaptive launcher icon

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

settings.gradle.kts

@@ -0,0 +1,17 @@
+pluginManagement {
+    repositories {
+        gradlePluginPortal()
+        google()
+        mavenCentral()
+    }
+}
+
+dependencyResolutionManagement {
+    repositories {
+        google()
+        mavenCentral()
+    }
+}
+
+rootProject.name = "CalendarrAndroid"
+include(":app")