`swarm-logs --help` documents the CLI surface but not the LogsQL
constructs an agent needs to build a bounded query with it: no
time predicate, and no way to know a bare word matches across the
whole swarm rather than one hive. Add a skill teaching `_time:`
predicates, hive/service scoping via the collector's stream
fields, message vs json format, distinguishing an empty result
from a refused request, and running a control query before
trusting an empty one.
Refs #4460
c95f721f81