HttpVHost::addRailsApp system default env can override custom env

Nobody has claimed this yet.

As written, the HttpVHost::addRailsApp function attaches the environment variables defined by pAppDefault->getEnv after the ones set by the options it's called with (and the ones it sets internally), which can cause failures in programs like RackRunner.rb to respect the custom environment. In particular, pAppDefault will have PATH set which will override any custom path set in a Virtual Host context, if I'm getting this right.

https://github.com/litespeedtech/openlitespeed/blob/d9610258f5c76ca204e1fd7074c23297b96a64de/src/http/httpvhost.cpp#L1712

could be replaced with something like
```
Env *pDefaultEnv = pAppDefault->getEnv();
if (pDefaultEnv)
{
for (const auto &var : *pDefaultEnv)
{
config.addEnvIfNotExist(var.c_str(), var.c_str());
}
}
```

Start in src/http/httpvhost.cpp around line 1712 and trace how HttpVHost::addRailsApp combines default, option-provided, and internal environment variables. Verify the precedence for PATH and other custom variables, then confirm that defaults fill only variables not already configured. Done means a Virtual Host’s custom environment is preserved while system defaults remain available.

Written by the indexing model from the issue text.