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/src/main/java/solutions/tretter/githugandroid/GitRuntime.kt

@@ -60,7 +60,7 @@ class GitRepositoryRuntime private constructor(
                 runGit(nativeGit, sandbox, listOf("checkout", "-B", desired.headBranch))
             }
 
-            materializeNativeGitState(nativeGit, sandbox, desired)
+            materializeNativeGitState(nativeGit, sandbox, desired, level.id)
         }
 
         return inspectSandbox(level)
@@ -385,7 +385,12 @@ class GitRepositoryRuntime private constructor(
         return body
     }
 
-    private fun materializeNativeGitState(nativeGit: File, sandbox: File, desired: RepoState) {
+    private fun materializeNativeGitState(nativeGit: File, sandbox: File, desired: RepoState, levelId: String) {
+        if (levelId == "push") {
+            materializeNativePushLevel(nativeGit, sandbox)
+            return
+        }
+
         desired.config.forEach { (key, value) ->
             runGit(nativeGit, sandbox, listOf("config", key, value))
         }
@@ -437,6 +442,42 @@ class GitRepositoryRuntime private constructor(
         }
     }
 
+    private fun materializeNativePushLevel(nativeGit: File, sandbox: File) {
+        sandbox.listFiles()
+            ?.filterNot { it.name == ".git" }
+            ?.forEach { it.deleteRecursively() }
+
+        fun writeFile(name: String, content: String = "$name\n") {
+            File(sandbox, name).apply {
+                parentFile?.mkdirs()
+                writeText(content)
+            }
+        }
+
+        fun commitIn(directory: File, message: String, vararg paths: String) {
+            runGit(nativeGit, directory, listOf("add") + paths)
+            runGit(nativeGit, directory, listOf("commit", "-m", message))
+        }
+
+        writeFile("file1")
+        commitIn(sandbox, "First commit", "file1")
+        writeFile("file2")
+        commitIn(sandbox, "Second commit", "file2")
+
+        val remoteWorkTree = File(sandbox.parentFile ?: sandbox, "${sandbox.name}-origin")
+        remoteWorkTree.deleteRecursively()
+        runGit(nativeGit, sandbox.parentFile ?: sandbox, listOf("clone", sandbox.absolutePath, remoteWorkTree.absolutePath))
+        runGit(nativeGit, remoteWorkTree, listOf("config", "receive.denyCurrentBranch", "ignore"))
+        File(remoteWorkTree, "file4").writeText("file4\n")
+        commitIn(remoteWorkTree, "Fourth commit", "file4")
+
+        writeFile("file3")
+        commitIn(sandbox, "Third commit", "file3")
+        runGit(nativeGit, sandbox, listOf("remote", "add", "origin", File(remoteWorkTree, ".git").absolutePath))
+        runGit(nativeGit, sandbox, listOf("fetch", "origin"))
+        runGit(nativeGit, sandbox, listOf("branch", "--set-upstream-to=origin/master", "master"))
+    }
+
     private fun filesForSetupCommit(files: List<GitFile>, index: Int, commitCount: Int): List<GitFile> {
         if (files.isEmpty()) return emptyList()
         if (commitCount <= 1) return files