Hooks decnet.canary.planter.seed_baseline into the deploy() flow's
fleet-mirror step. After upserting a FleetDecky as 'running' we seed
the configured baseline canary set on the freshly-deployed decky.
Persona detection: read d.nmap_os (Windows -> windows path-mapping,
otherwise linux). Failures are logged and surface as state=failed
rows in the UI; the deploy itself MUST NOT abort (resilience
principle in CLAUDE.md).
Tests confirm:
- seed_baseline produces one row per configured generator per decky;
- the deployer source wires seed_baseline inside a try/except so a
failure can't abort the deploy.