Restructure Code for reuse and best practices

[chrisma]

It seems we have settled on same base technologies and frameworks, including Bootstrap, JavaScript (possibly with Bootstrap JQuery plugins) and NPM.

Therefore, we should make sure that the code conforms to these standards and best practices.

• NPM has a nice starter that our content could be copied into: https://github.com/twbs/bootstrap-npm-starter
• Bootstrap offers an example dashboard layout that could be adapted: https://getbootstrap.com/docs/5.1/examples/dashboard/
• Code duplication (such as the navbar) should be reduced, e.g. through iframes, by loading partials with JS by hand, by using a partial library or a full templating engine