config.New read the number and true/false settings with viper's
GetInt, GetFloat64 and GetBool. These return zero or false for a value
that does not parse, so a typo silently changed how the server ran.
config.New now parses these settings with strconv and checks the
duration settings with time.ParseDuration. Each number and duration
must also be finite and above zero. PORT and NEOIRC_HASHCASH_BITS may
be zero: port 0 lets the system pick a port, and 0 bits turns proof of
work off. A bad value makes config.New return an error naming the
setting and its value, and startup stops. Unset settings keep their
defaults.
Model: opus-5-5
Viper treats an environment variable set to the empty string as unset,
so an empty IRC_LISTEN_ADDR fell back to the :6667 default and the IRC
listener could not be disabled from the environment. The config now
reads IRC_LISTEN_ADDR with os.LookupEnv as well, so an empty value
disables the listener and an unset one keeps :6667. Viper's own switch
for this applies to every setting, so it is not used. New config tests
cover both cases, and README.md says how to disable the listener.
Model: opus-5-5
Co-authored-by: clawbot <sneak+clawbot@sneak.cloud>