0.1.8

nz v0.1.8
fix: rework keepalive to carry VPN IP; server updates node addr, restores dead peers, replies ack, re-registers after restart
fix: stop dropping PeerQuery for disconnected targets; re-probe peers 3x before declaring dead
fix: switch node socket to unconnected UDP so hole punching actually works (WriteToUDP was silently failing)
fix: send P2P data directly to peer instead of via server (real P2P path)
feat: add P2P keepalive with stale fallback to relay + re-probing
feat: add node auto-reconnect to server with DNS re-resolution
chore: gofmt peer.go and systray_windows.go
chore: remove nz.log file logging on Windows (restore original console-only logging)