Replace docs/images screenshots (runs-board, run-detail, workflow-example)
with fresh captures from the current FABRO-branded UI in demo mode.
Also fix a panic in arc-api demo::run_config_to_api where None-valued
HashMap fields (e.g. sandbox.env) serialized to JSON null, which failed
to deserialize into non-optional HashMap fields in RunConfiguration.
Added strip_nulls helper to clean the intermediate JSON value.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
- runs-board: removed browser tabs and address bar
- run-detail and workflow-example: removed browser chrome, Arc nav, and cropped sides
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
- Add runs board screenshot to introduction page
- Add run detail and workflow diagram screenshots to why-arc page
- Add private research preview warning to quick-start page
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>