[G064] Horizontal scaling

[github-actions]

Metadata

• Gap ID: G064
• Status: Partial
• Workstream: WS5
• Phase: 5
• Priority: high

Problem

Current state and gap from feature audit.

Scope

• Backend/API changes
• UI/UX changes
• Data model/migrations
• Docs updates (docs/ + docs-site/src/content/docs/)

Acceptance Criteria

• Feature behavior complete
• Authorization/security checks in place
• Unit/integration/e2e tests added
• lint + typecheck + tests pass
• Docs updated in both doc trees

Technical Notes

Relevant files/modules, rollout/rollback plan, migration details.

Source

• Checklist: github-issues-checklist.md
• Roadmap: notimplemented.md