feat(file-history): mark latest history entry identical to working tree

Annotate file history entries with matches_working_tree and surface that
information in the UI so the most recent commit can be identified as
"current version" when its content equals the working tree.

- Backend: add FileHistoryCommit and annotate_file_history(...) which checks
  (only for regular files) whether the newest commit's blob matches the
  working tree via `git diff --quiet`. list_file_history now returns the
  annotated commits.
- Types: add optional matches_working_tree to GitCommit shape used by the UI.
- UI: show a "Current version"/"Aktueller Stand" badge and disable Diff/Restore
  actions for entries that match the working tree (text localized for de/en).

Also add a test that verifies the matching behavior across file edits,
staging, committing and deletion. No external API breaking changes.

src-tauri/src/git.rs

@@ -4334,6 +4334,29 @@ pub async fn list_repository_files(path: String) -> Result<Vec<GitRepositoryFile
     .await
 }
 
+#[derive(Debug, Serialize)]
+pub struct FileHistoryCommit {
+    #[serde(flatten)]
+    commit: GitCommit,
+    matches_working_tree: bool,
+}
+
+fn annotate_file_history(repo: &Path, file: &str, commits: Vec<GitCommit>, cancellation: Option<&SearchCancellation>) -> Result<Vec<FileHistoryCommit>, String> {
+    // Keep folder history unchanged: Git diff would omit untracked children.
+    let regular_file = fs::symlink_metadata(repo.join(file)).is_ok_and(|metadata| metadata.is_file());
+    let mut result = Vec::with_capacity(commits.len());
+    for (index, commit) in commits.into_iter().enumerate() {
+        check_search_cancelled(cancellation)?;
+        let matches_working_tree = index == 0 && regular_file && run_git_cancellable(
+            repo, ["diff", "--quiet", "--no-ext-diff", "--no-textconv", &commit.hash, "--", file],
+            cancellation, "Could not compare current file version",
+        ).is_ok();
+        check_search_cancelled(cancellation)?;
+        result.push(FileHistoryCommit { commit, matches_working_tree });
+    }
+    Ok(result)
+}
+
 #[tauri::command]
 pub async fn list_file_history(
     path: String,
@@ -4341,7 +4364,7 @@ pub async fn list_file_history(
     limit: Option<u32>,
     request_id: Option<String>,
     state: tauri::State<'_, SearchCancellationState>,
-) -> Result<Vec<GitCommit>, String> {
+) -> Result<Vec<FileHistoryCommit>, String> {
     let state = state.inner().clone();
 
     tauri::async_runtime::spawn_blocking(move || {
@@ -4354,7 +4377,8 @@ pub async fn list_file_history(
             search_id: request_id.clone(),
         });
 
-        let result = list_file_history_core(&repo, file, limit, cancellation.as_ref());
+        let result = list_file_history_core(&repo, file.clone(), limit, cancellation.as_ref())
+            .and_then(|commits| annotate_file_history(&repo, &file, commits, cancellation.as_ref()));
 
         if let Some(request_id) = request_id.as_deref() {
             let _ = state.clear(request_id);
@@ -10275,6 +10299,25 @@ mod tests {
         assert_eq!(commits[1].summary, "init");
     }
 
+    #[test]
+    fn file_history_marks_only_an_identical_current_file() {
+        let repo = init_temp_repo("history_current_version");
+        commit_initial_file(&repo.path);
+        let matches = || {
+            let commits = list_file_history_core(&repo.path, "old.txt".into(), Some(10), None).unwrap();
+            annotate_file_history(&repo.path, "old.txt", commits, None).unwrap()[0].matches_working_tree
+        };
+        assert!(matches());
+        fs::write(repo.path.join("old.txt"), "local changes\n").unwrap();
+        assert!(!matches());
+        run_git_test(&repo.path, ["add", "old.txt"]);
+        assert!(!matches());
+        run_git_test(&repo.path, ["commit", "-q", "-m", "updated"]);
+        assert!(matches());
+        fs::remove_file(repo.path.join("old.txt")).unwrap();
+        assert!(!matches());
+    }
+
     #[test]
     fn list_file_history_returns_commits_for_selected_folder() {
         let repo = init_temp_repo("folder_history");