Border color with transparency

Editor assessment

The subject states the feature — border colors support transparency — which names the capability but not the component or the motivating use case, so the reader must consult the diff for specifics. The body is a squash-merge bullet list that narrows it (`feat: progress remaining color with rgba(0, 0, 0, 0.06)`), revealing that the Progress component's remaining-track color is the concrete application. Type `feat` is accurate; absent scope is a real gap where `progress` would have anchored the change. Footers are absent. Understandable and honest, but the component-level specificity arrives only in fragments, leaving mediocre teaching value.