Replace the English docs/rbac.md with a comprehensive Chinese
docs/RBAC说明.md and a wiki-style summary under docs/wiki/安全认证/.
Explain how tenant RBAC relates to the shared space feature (they
are orthogonal: tenant RBAC is the vertical defense, shared space
is the horizontal collaboration channel) and cross-link the two
docs in both the flat and wiki trees. Update inbound references in
.env.example, docker-compose.yml, and the auth legacy env test to
point at the new file name.
wizardchen
7ebb29cd3e