Two small observability follow-ups to the phase-1 agent/topology wiring:
TopologySummary now carries needs_resync so operators can see the
heartbeat's resync flag via the topology list/detail API without
dropping into the DB.
TopologyStore.record_error becomes an upsert — when a docker/compose
failure fires during the first materialise (put() never reached), we
still land a marker row so GET /topology/state surfaces the error and
the next heartbeat carries an empty applied_version_hash. That empty
hash is what master's heartbeat check relies on to flag the topology
for resync instead of assuming the apply succeeded.
anti
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