the current proxy target IP address is probably only working for a
single developer at a time. this change introduces a vite.user.ts, which
is ingored by GIT, and which can define a proxy_target that works for
the respective developer.
this does not change the default behavior, as the fallback value is
still the old IP address. if the new vite.user.ts file does not exist,
or if it does not export proxy_target, the fallback value is used.
file vite.config.ts adds an example in a comment of how to bootstrap a
vite.user.ts.
