Support for alternate base url about flatnotes

[dullage]

I'm currently working on a complete rebuild of the web UI in Vue 3 with Vue Router. As part of this work I should be able to allow for a path prefix to be set at build time.

Unfortunately I can't see a clean way to implement a runtime option but hopefully a build option will suffice for those that need it.

[fawick]

Having a maintained way to set the base URL to a subfolder would be great, indeed.

First, I tried to come up with a solution by adding the --root_path option to the uvicorn call in entrypoint.sh but that was not enough. The browser tried to load the front-end assets without the subfolder.

Second, I added the base option to vite.config.js. That helped with the JS assets, but all requests to /api/* are still failing (e.g. /api/config or /api/notes/[...]).

[Code-Otto]

Also check out #49 (And PR #135), there's been a prior attempt at this but disregarded because of the added complexity

I'd appreciate the addition of such a feature since this is the last missing straw for proper Flatnotes integration in my home server

[fawick]

Thank you @Code-Otto for making me aware on the prior work.

As it looks, #135 is probably rendered obsolete by the switch from Parcel to Vite (and #135 was rejected anyway).