Fix Push level native repository setup

- Materialize the Push level with a real local/remote Git fixture that shares the first two commits, adds a remote-only fourth commit, and leaves a local third commit to rebase.
- Strengthen Push validation to require the rebased/pushed state and all expected files instead of only checking that a push command happened.
- Keep the level solution tests exercising the same native sandbox shape users see in the app.

app/build.gradle.kts

@@ -19,8 +19,8 @@ android {
         applicationId = "solutions.tretter.githugandroid"
         minSdk = 26
         targetSdk = 35
-        versionCode = 119
-        versionName = "0.1.118"
+        versionCode = 120
+        versionName = "0.1.119"
 
         testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
         vectorDrawables.useSupportLibrary = true