fix: serve peer list from daemon snapshot

[LiranCohen]

Summary

• materialize an immutable, rich last-good mesh snapshot inside the running daemon
• serve meshd peer list from the validated local status socket before loading the identity vault or querying DWN
• preserve the prior snapshot and expose refresh metadata when a remote rebuild fails
• retain the existing remote path for old daemons, legacy state, mismatched profiles, and snapshots that are not ready
• keep the tray/status peers backward compatible while adding node identity, ownership, label, expiry, and last-seen fields

Verification

• go build ./...
• go vet ./...
• go test ./... -count=1 -race

Closes #252