fix(build): Use merge-base commit SHA as base reference instead of branch name

Previously the base ref detection would only work if a local branch pointed
to the exact merge-base commit. This implementation now returns the
merge-base commit SHA directly, enabling automatic base reference detection
in all cases where a merge-base can be determined.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: runningcode

src/commands/build/upload.rs

@@ -178,11 +178,11 @@ pub fn execute(matches: &ArgMatches) -> Result<()> {
                 repo_ref
                     .and_then(|r| match git_repo_base_ref(r, &cached_remote) {
                         Ok(Some(base_ref_name)) => {
-                            debug!("Found base branch reference: {}", base_ref_name);
+                            debug!("Found base reference: {}", base_ref_name);
                             Some(base_ref_name)
                         }
                         Ok(None) => {
-                            warn!("No base branch reference found (no local branch points to merge-base)");
+                            warn!("No base reference found (could not determine merge-base)");
                             None
                         }
                         Err(e) => {

src/utils/vcs.rs

@@ -292,22 +292,10 @@ fn find_merge_base_ref(
     let remote_commit = remote_ref.peel_to_commit()?;
     let merge_base_oid = repo.merge_base(head_commit.id(), remote_commit.id())?;
 
-    // Try to find a branch name that points to this commit
-    let branch_name = repo
-        .branches(Some(git2::BranchType::Local))?
-        .flatten()
-        .find_map(|(branch, _)| {
-            let branch_commit = branch.get().peel_to_commit().ok()?;
-            if branch_commit.id() == merge_base_oid {
-                let branch_name = branch.name().ok()??;
-                debug!("Found base branch reference: {}", branch_name);
-                Some(branch_name.to_owned())
-            } else {
-                None
-            }
-        });
-
-    Ok(branch_name)
+    // Return the merge-base commit SHA as the base reference
+    let merge_base_sha = merge_base_oid.to_string();
+    debug!("Found merge-base commit as base reference: {}", merge_base_sha);
+    Ok(Some(merge_base_sha))
 }
 
 fn find_reference_url(repo: &str, repos: &[Repo]) -> Result<Option<String>> {