mara's review point on #4351: an agent isn't pinned to a hive forever
(it can move), so a URL naming one would go stale the moment it did.
Resolve the hive at request time from the agent-status bucket instead
-- the same source AgentStatusRow.hive already comes from -- rather
than trusting a caller-supplied value. Route is now
GET /api/agents/{name}/term/stream; a never-reported agent now answers
404 (no hive on record) instead of silently guessing.
hive-agent already publishes classified TermMsg rows to the core NATS
subject $SWARM.term.{hive}.{agent} -- live only, no retention, by
design. This endpoint subscribes that subject per request and relays
each row over SSE, opaque to this daemon (no TermMsg dependency, same
pass-through shape crate::status already uses for hive snapshots).
No replay/history: the publish side never grew JetStream retention, and
this route's own job (a live tail) never needed it.
