docs: promote documentation governance - #103

Summary

• promotes nearest-owner repository-family authority and public Docs/current engineering separation into the durable Scient documentation policy
• defines the logical Help, Capabilities, Architecture, Development, Operations, Upstream, and Records roles without requiring folder migration
• adds update-before-create, gradual-feature ownership, temporary-artifact, and bounded fan-out rules
• adds the single proportional Documentation impact declaration and dependent-PR ordering to the shared contribution protocol
• keeps AGENTS.md and the documentation index as thin routes

Dependency

Stacked on accepted-plan PR #101. Repository-local public rules are self-contained in dependent desktop and website PRs.

Documentation impact: Updated — AGENTS.md, docs/README.md, docs/documentation-policy.md, docs/operations/team-contribution-protocol.md, and the accepted implementation plan

Validation

• Markdown formatting passed
• local Markdown links passed
• git diff --check passed
• no Scient-agent inspection or change