v0.21.0

Added

• Admins can give a capability to everyone at a membership level: /admin capabilities grant-level level:member capability:ha-lights (and revoke-level). A friend grant reaches members too. It's saved in a new optional tiers: section of members.yaml, audited like other access changes, and DMs nobody. A person holds their own grants plus their level's, so promoting or demoting someone changes them at once; being an admin still gives none. /admin capabilities list shows which levels a capability reaches and marks what a person gets from their level. See ADR 0019.