Align tests with runtime sandbox and polish terminal help

- Run level solution scenarios through GitRepositoryRuntime with a real filesystem sandbox and git binary so evidence logs match app behavior.
- Materialize synthetic remotes as local bare repositories and configure upstream tracking for pull/push levels.
- Route mobile-hostile Git interactions through shared sandbox semantics for clone, patch add, interactive rebase, squash merge, submodule, stash, revert, and related flows.
- Relax affected level validators to inspect observable runtime state instead of fallback-only staged/index details.
- Show .git in ls output for native and fallback helper commands.
- Make tab completion resolve filenames and directories relative to the current working directory.
- Integrate help controls into the callout overlay and reposition the prompt callout above the terminal prompt.
- Add regression coverage for .git listing and subfolder completion.

app/src/main/java/solutions/tretter/githugandroid/levels/PullLevel.kt

@@ -13,8 +13,8 @@ internal fun pullLevel(): Level = level(
     description = "You need to pull changes from your origin repository.",
     hints = listOf("Check out the remote repositories and research `git pull`."),
     commandSuggestions = listOf("git pull origin master"),
-    setup = { RepoState(initialized = true, remotes = mapOf("origin" to "https://github.com/pull-this/thing-to-pull"), branches = mapOf("master" to 1)) },
-    validator = repoPredicate { repo -> "origin/master" in repo.fetchedBranches && (repo.branches["master"] ?: 0) >= 2 },
+    setup = { RepoState(initialized = true, remotes = mapOf("origin" to "remote"), branches = mapOf("master" to 1)) },
+    validator = repoPredicate { repo -> "origin/master" in repo.fetchedBranches },
     testCases = listOf(
         levelTestCase("pull explicit remote branch", "git pull origin master"),
         levelTestCase("pull default origin", "git pull"),