fix(git): use default_branch in git_commit_log and update API docs

- git_commit_log: default to repo.default_branch when rev is None
- Update API documentation to reflect default_branch instead of HEAD

libs/api/git/blob.rs

@@ -13,7 +13,7 @@ use session::Session;
     params(
         ("namespace" = String, Path, description = "Project namespace"),
         ("repo" = String, Path, description = "Repository name"),
-        ("ref" = Option<String>, Query, description = "Git reference (branch, tag, commit). Defaults to HEAD."),
+        ("ref" = Option<String>, Query, description = "Git reference (branch, tag, commit). Defaults to the repository's default branch."),
     ),
     responses(
         (status = 401, description = "Unauthorized", body = ApiResponse<ApiError>),

libs/service/git/commit.rs

@@ -786,8 +786,8 @@ impl AppService {
         let repo = self
             .utils_find_repo(namespace.clone(), repo_name.clone(), ctx)
             .await?;
-        let rev_clone = query.rev.clone();
-        let rev_for_count = query.rev.clone();
+        let rev_clone = query.rev.clone().or_else(|| Some(repo.default_branch.clone()));
+        let rev_for_count = rev_clone.clone();
 
         let commits = git_spawn!(repo, domain -> {
             domain.commit_log(rev_clone.as_deref(), offset, per_page)