Org hire from knowledge + branch defaults

Company onboarding from the org knowledge base enters the roadmap; `dev` is the default git branch.

What changed

Joining a company will be driven by organisation and department knowledge: workmail, pay pocket, access, and onboarding tasks run as an owner-overridable playbook — not a static form.
That work is sequenced as Phase 5 after the personal AGI confirm loop (Phase 4). Later phases cover shared calendars/files, then chat/meeting, then docs/marketplace.
Git default branch is dev. Day-to-day code lands on dev, then promotes dev → sot → prod. Only those three branches remain.

Operators: see repository .github/BRANCHING.md. Product shape: docs/implementation_plan.md §24.