feat: enhance host and port parsing to support IPv6 addresses

[podrivo]

Closes #769

Problem

The CLI split the target on every colon (target.split(':')), so IPv6 addresses broke — the first internal colon was treated as the host/port separator, even in bracketed form ([2001:db8::1]:27015):

$ gamedig --type minecraft [2409:8a55:...:3ed1]:25565 --debug
  host: '[2409'
Q#0 Query failed with error Error: Invalid domain

Fix

Reworked host/port parsing in bin/gamedig.js. Besides the bracketed form, colon count disambiguates: exactly one colon means host:port; zero or 2+ means the whole string is the host (hostnames, IPv4, unbracketed IPv6).

if (argv._.length >= 1) {
  const target = String(argv._[0])
  const bracketed = target.match(/^\[(.+)\](?::(.+))?$/)
  if (bracketed) {
    options.host = bracketed[1]
    if (bracketed[2]) options.port = bracketed[2]
  } else if (target.split(':').length === 2) {
    [options.host, options.port] = target.split(':')
  } else {
    options.host = target
  }
}

No downstream changes needed: DnsResolver.resolve() already short-circuits valid IPs via isIP(host).

Compatibility

Hostnames, IPv4, and host:port parse identically to before — only the broken IPv6 cases change. String(...) guards against Minimist coercing a numeric-only host to a number.

Testing

• Verified the issue repro now parses correctly and reaches a TCP connection attempt.
• Diffed old vs. new parsing across all input types — identical for valid existing inputs.
• npm run lint:check passes.