Cloned miniPC images share the same MachineGuid, so their client_id
collides and only one host appears in the list. Fold the hostname into
the V2 client-ID hash so hosts with distinct names no longer collide.
Already-persisted client IDs are unchanged: they recompute only after
the settings/client_id registry value is cleared.
Server side, when a login reuses an existing client_id but the hostname,
IP, or username differs, emit a WARN diagnostic before assigning the
connection to the standby list. Observation-only, no behavior change.
Co-Authored-By: deepseek-v4-pro
