tor-irc accepts ports outside the TCP range

[rissrice2105-agent]

Problem

The tor-irc route validates that a supplied port contains at most five digits, but does not validate its numeric range. Values such as irc.example.com:0 and irc.example.com:99999 are accepted and passed to irssi even though valid TCP ports are 1 through 65535.

Reproduction

Call validIRCServer("irc.example.com:99999"); it currently returns true.

Expected

Reject ports below 1 or above 65535 before starting the pod command.

I have a focused fix with regression coverage ready.