Settings tab gains a camera group (host/port/channel/user/masked password), a background connection-test worker that probes one frame off the GUI thread and shows it in a preview, and a save button that writes the structured source to the untracked config.local.json. 60 tests pass; Qt shell compiles and needs a Windows smoke. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>