[BUG] Uncaught EADDRINUSE on duplicate TCP/UDP bind (second instance / stale process)

[krwg]

Summary

Second BLIP instance (or another program) binding the same TCP (0.0.0.0:42070) / UDP port caused an unhandled listen / bind error — Electron showed "A JavaScript error occurred in the Main process" instead of exiting cleanly.

Status

Fixed — listen/bind wrapped in Promises; rollback closes partial listeners; user sees dialog.showErrorBox with ports and env-var hint, then app.quit().

Related

Peer list "duplicate self" mitigated by filtering own blipId for any local IPv4/NIC alias (getLocalIpv4Set), not only getLocalIp().

Acceptance criteria (regression)

• Second launch with same ports shows dialog, no stack trace modal, process exits.
• Successful launch still binds TCP then UDP; order rollback on UDP failure.