fix(dns): fall back to public resolver when system DNS is unreachable

[BabyBear7]

Summary

checkSrv currently swallows every error and returns null, which means getServerStatus silently falls back to the default 25565 port whenever the system DNS resolver is broken. For servers that expose their Minecraft port only through SRV records, this makes them show as permanently offline even though the server is up.

This showed up in the wild with the Node.js 22 + Windows c-ares regression tracked in nodejs/node#62326 / #62347. Newer c-ares (bundled in Node 22.22.0, 24.13.0+, 25.x < 25.6.1) reports the loopback fallback with tcp_port/udp_port = 53 instead of 0. Node's glue layer still checks for port 0 to detect the fallback, misdetects, and ends up firing DNS queries at 127.0.0.1:53 which has no listener — hence ECONNREFUSED querySrv. The fix (nodejs/node#61453) is in 25.6.1 and 24.x but not yet backported to the 22 LTS line, so Electron apps on Electron 39 (which bundles Node 22) are currently exposed.

Change

When resolveSrv rejects with a network-layer error code (ECONNREFUSED, ECONNRESET, ETIMEDOUT, ESERVFAIL, EREFUSED), retry once against a user-independent public resolver (1.1.1.1, 8.8.8.8) using an explicit Resolver instance. Legitimate "no SRV record" responses (ENOTFOUND, ENODATA, etc.) still short-circuit to null, so the extra lookup only happens when the system resolver is actually broken.

A single logger.warn line identifies the failing error code so launcher operators can tell whether the fallback kicked in.

Reproduction before the patch

On a Windows host running Node 22.22.0:

> node -e "console.log(require('dns').getServers())"
[ '127.0.0.1' ]
> node -e "require('dns/promises').resolveSrv('_minecraft._tcp.<srv-host>').then(console.log, e => console.error(e.code))"
ECONNREFUSED

Same host on Node 20.18.1 returns the correct SRV record and the real system DNS servers. With this patch, checkSrv transparently recovers on Node 22 by retrying through the public resolver, and getServerStatus hits the correct port.

Test plan

• npm run build — clean TypeScript compile
• npm run lint — no new warnings
• Existing ServerStatusAPITest (real-network test) runs unchanged in working environments (fast path untouched)
• Manual verification on a Windows 22.22.0 host against an SRV-only server (passes through fallback path and returns status)