fix/parsing-envs

[PaulDalek]

Corrected the way envs are parsed with Zod and some other minor fixes.

[jszuminski]

Looking great!

Not so sure about the HIGHCHARTS_CORE name instead of HIGHCHARTS_CORE_SCRIPTS, I'm not sure which would be more intuitive and more informative here, but I guess it's a matter of preference, so no difference to me.

[PaulDalek]

@jszuminski Renamed the HIGHCHARTS_MODULES and HIGHCHARTS_INDICATORS environment variables respectively to HIGHCHARTS_MODULE_SCRIPTS and HIGHCHARTS_INDICATOR_SCRIPTS and left the HIGHCHARTS_CORE_SCRIPTS as it was before.