Add Co-authored-by trailers to Merge's squash commit

internal/server/server.go

@@ -301,6 +301,21 @@ func (s *Server) GetUnmerged(w http.ResponseWriter, r *http.Request, taskID stri
 	})
 }
 
+func (s *Server) GetCoAuthors(w http.ResponseWriter, r *http.Request, taskID string) {
+	_, err := s.store.GetTask(r.Context(), taskID)
+	if err != nil {
+		writeStoreError(w, err)
+		return
+	}
+
+	coAuthors, err := s.agents.CoAuthors(r.Context(), taskID, actor(r))
+	if err != nil {
+		writeError(w, http.StatusInternalServerError, err)
+		return
+	}
+	writeJSON(w, http.StatusOK, coAuthors)
+}
+
 func (s *Server) MergeTask(w http.ResponseWriter, r *http.Request, taskID string) {
 	t, p, ok := s.activeTask(w, r, taskID)
 	if !ok {