Persist the default Git diff layout

src/app/git.rs

@@ -40,13 +40,6 @@ pub(super) struct GitWorktree {
     pub(super) files: Vec<GitFile>,
 }
 
-#[derive(Clone, Copy, Debug, Default, Eq, PartialEq)]
-pub(crate) enum GitDiffMode {
-    #[default]
-    Unified,
-    Split,
-}
-
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
 pub(super) enum GitDiffLineKind {
     Section,
@@ -186,6 +179,7 @@ impl App {
         match load_diff(&worktree.root, file, &self.config.git) {
             Ok(diff) => {
                 self.git_diff = Some(diff);
+                self.git_diff_layout = self.config.git.diff_layout;
                 self.error = None;
             }
             Err(error) => self.error = Some(error),
@@ -1113,6 +1107,7 @@ mod tests {
             .find(|file| file.display_path == "changed.txt")
             .unwrap();
         let settings = GitConfig {
+            diff_layout: GitDiffLayout::Unified,
             diff_algorithm: GitDiffAlgorithm::Patience,
             context_lines: 0,
             interhunk_lines: 0,