Starts DashboardServer on port 7777 (or --dashboard-port), uses its
reporter as ctx.dashboard, auto-opens the URL via xdg-open/open/start.
Cleans up on exit. WS client connections logged as info events so
you can see when the browser attaches.
Verified: 2-account populate run with --watch=dashboard serves the
static page on :7777, accepts WS connections, cleanly shuts down
when the run completes.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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