[Feature] Complete local install / no JavaScript needed from internet

[Stefan-Olt]

I just started testing Borgitory and it looks really great and offers great features. But I found one rather unfortunate issue: When you open it in a web browser it loads JavaScript from unpkg, jsdeviler and tailwindcss. I think that is an issue for the following reasons:

• Not all clients accessing the Borgitory web-interface may have Internet access. Either for security reasons or there could be a temporary issue with the internet connection.
• Borgitory becomes inaccessible if unpkg, jsdeviler or tailwindcss fails: Just remember the recent downtimes of AWS and Cloudflare. Especially in this situations you may need to access your backups, but if one of those sites is affected by such an issue Borgitory will not work anymore
• I know this is a rather theoretical issue: Your backups may contain sensitive data. Usually due to same-origin-policy JavaScript from another source cannot "phone home" directly from the browser. But it could change the way borgitory works and borgitory may start acting maliciously. This would of course need to be a very targeted attack.

It would be great if either borgitory could host all those assets locally, either by default, or a option to download/install these dependencies and load them from the borgitory install.

[Stefan-Olt]

A quick-and-dirty solution: Just download the JS files and then place them into assets/js and then edit base.html and login.html to use the local versions. I will not create a pull request for that, as there is probably a better solution, like downloading the current versions of the files during installation