pluginCodePaths
Where a hybrid server's plugins live, so a script can import plugin APIs. A plugin host overrides this and asks the plugin manager.
Return
null where the host cannot enumerate plugins at init, because its own init runs before the first plugin loads — an empty list would be indistinguishable from "no plugins". ReplBridge gates the compile classpath on exactly that null; the jars themselves come off the live loaders either way.