Dark mode: “Connect a repository” panel renders with light background, breaking theme consistency

On the Repositories page in dark mode, the panel containing the “Connect a repository” button renders with a white/light background instead of the dark theme background used elsewhere on the page. This creates a jarring visual inconsistency, and the helper text below the button (“Connect your GitHub account on the GitHub tab to verify and claim repositories.”) has poor contrast against the light background, making it hard to read.