chore: remove obsolete Android app configuration files

- Deleted build.gradle.kts, gradle.properties, and gradlew files as part of the cleanup process.
- Removed local.properties and various generated files from the .gradle directory to streamline the project structure.
- Cleared out unnecessary build artifacts and intermediate files to improve project maintainability.

mobile-app/settings.gradle.kts

@@ -0,0 +1,20 @@
+pluginManagement {
+    repositories {
+        google()
+        mavenCentral()
+        gradlePluginPortal()
+        maven("https://maven.pkg.jetbrains.space/public/p/compose/patch")
+    }
+}
+
+dependencyResolutionManagement {
+    repositories {
+        google()
+        mavenCentral()
+        maven("https://maven.pkg.jetbrains.space/public/p/compose/patch")
+    }
+}
+
+rootProject.name = "Trainingstagebuch"
+include(":composeApp")
+include(":shared")