Permission::default_for and hive-sh4re's MANAGER_AGENT are gone: every
agent with no permissions key holds Permission::DEFAULT, ruth included.
The agent-name parameters that only fed default_for go with it
(permissions::effective, HiveCopy::before_read/after_read and their
callers).
swarm-controller seeds the grant ruth held by name: at start, a declared
ruth whose permissions are unset gets DEFAULT plus manage_root_agent
written into her key, once, logged. A set key is never touched. It is a
one-shot to delete once every swarm has passed it.
The swarm UI setup assistant opens the create form with
manage_root_agent checked, so a new ruth is created with the grant.
permissions_import no longer adds ruth to the import or splits her
default. Docs and help text no longer say ruth holds the grant by
default; swarmctl-cli.md regenerated.
The queue's payload ceiling was justified by what the queue was about to
carry; it carries it now, so the comment says so.
The other two sites say "a hive with no queue configured". The swarm has
exactly one queue and a hive cannot lack it — only its coordinates, its
credential, or its ability to reach it. That wording is already used
everywhere else the absence is named; these two predate it.
The docs section on the agents' queue coordinates stopped at delivering
them and never said what the connection is for. It now names the subject
and the degrade rule, which is the part an operator reading an agent's
terminal at the swarm needs.
Refs #3805
