Inserts a per-type threshold lookup before the global AgentDefaults.Disk
fallback in CheckHost's disk evaluation. inferDiskHardwareType maps the
disk device path to "nvme" (only NVMe is inferable today); when the
DiskFillByType map carries a matching key, that hysteresis threshold is
used, otherwise evaluation falls through to the existing global default.
Storage-type unified_eval branch is unchanged.
Tests prove: (a) NVMe device at 91% does not alert when DiskFillByType
sets the nvme trigger to 92; (b) the same device at 93% alerts at the
nvme threshold; (c) /dev/sda1 falls back to the global threshold; (d)
the storage-type alert branch is not regressed.
Move host-agent identity, metric projection, disk/SMART/RAID/Unraid health handling, cleanup, and offline lifecycle into internal/alerts/host.go.
Keep shared health-assessment evaluation package-level for now because storage ZFS and host SMART/RAID still share that bridge, while recording host.go as the host checker owner in the alerts subsystem contract.
Proof: go test ./internal/alerts/...
rcourtman