Web UI: Changes vite dist asset paths to relative

[psychedelicious]

Adds base: '', to vite config.

The resultant change in the build frontend is that asset paths are relative instead of absolute, e.g.:

<link rel="stylesheet" href="/assets/index.58175ea1.css"> ==> <link rel="stylesheet" href="./assets/index.556a5ea7.css">

I believe hope this resolves #1159 and shouldn't affect anything else.

[psychedelicious]

I've converted this to a draft, pending @steverweber reviewing.

[blessedcoolant]

Seems fine. Just double check with the docs here once: https://socket.io/docs/v4/client-options/

It seems the only requirement is that the client and server side pathname should always remain the same.

[psychedelicious]

@blessedcoolant , I made another change and got this working for the requester, and both normal and dev servers still work fine. Can you please test this and re-review the changes?

[psychedelicious]

The default server path is the same, and we aren't specifying it, so I suppose we are all clear.

[steverweber]

regarding socket.io "The server and the client values must match (unless you are using a path-rewriting proxy in between)." in the issue case there's a proxy.