Align level parity docs and fetch/status validation

- Add LevelsCompare.md with setup and validation comparisons against Gazler/githug.
- Document that LevelsCompare.md must be updated when level behavior changes.
- Track FETCH_HEAD count in RepoState so the Fetch level can match upstream validation.
- Mirror upstream Status setup with staged files plus untracked database.yml.
- Keep Fetch from being solved by pull despite native Git FETCH_HEAD behavior.
- Bump app version and build debug APK.

app/src/test/java/solutions/tretter/githugandroid/LevelSolutionsTest.kt

@@ -101,7 +101,8 @@ class LevelSolutionsTest {
     @Test
     fun reportedRegressionCommandsDoNotSolveLevels() {
         val statusRepo = statusLevel().setup()
-        assertEquals(listOf("database.yml"), statusRepo.files.map { it.name })
+        val untrackedStatusFiles = statusRepo.files.filter { !it.staged && !it.tracked && !it.deleted }.map { it.name }
+        assertEquals(listOf("database.yml"), untrackedStatusFiles)
 
         val gitBinary = testGitBinary()
         val runtimeRoot = testSandboxRoot().apply {
@@ -185,6 +186,7 @@ class LevelSolutionsTest {
             appendLine("config=${config.toSortedMap()}")
             appendLine("stashes=$stashes")
             appendLine("fetchedBranches=${fetchedBranches.sorted()}")
+            appendLine("fetchHeadCount=$fetchHeadCount")
             appendLine("pushedBranches=${pushedBranches.sorted()}")
             appendLine("pushedTags=${pushedTags.sorted()}")
             appendLine("submodules=${submodules.toSortedMap()}")