Drag the queue button panel onto the top actionbar to dock it, and drag
the handle out (past a threshold) to float it again. Docking reuses
ComfyUI's ComfyButtonGroup / actionbar `.border-dashed` reveal hook, and
the mode is persisted in a cookie. The dock feature is opt-in via a new
D2_FloatContainer option so the shared PromptConvert / ProgressPreview
panels are unaffected.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>