deploy_topology and teardown_topology now branch on
target_host_uuid. When set:
- Hydrate the topology locally (validator runs exactly as before).
- Compute canonical_hash; push {hydrated, version_hash} to the
pinned agent through AgentClient.apply_topology.
- Status machine still moves PENDING -> DEPLOYING -> ACTIVE on 2xx,
PENDING -> DEPLOYING -> FAILED on error; master remains the sole
owner of the row.
Teardown flips to TEARING_DOWN, fires /topology/teardown, then
TORN_DOWN — we log a warning on agent error but still settle to
TORN_DOWN so operators can delete the row (agent garbage is cleaned
on the next re-enroll).
Unihost deploys are unchanged — the field defaults to NULL so every
existing flow takes the local path.
Step 6 of the agent <-> topology integration.
