What will help for a layer like meta-qt6 where every LayerBranch needs to be mapped to a different upstream git branch is a UI table view showing all the LayerBranches for a given LayerItem and the actual_branch to "stable" branch mapping. We could also probably add a "Updates enabled" check box next to each branch to allow admin/staff users to rapidly change all of a layer's updates at the same time. Perhaps a "Manage Layer Branches" button would take the user to this view. Layer maintainers would be able to set the actual_branch fields. And perhaps an "Add Layer Branch" button could be at the bottom to allow missing branches to be added...