Choose and document a style guide for HTML, CSS, and JS

Description or user story

We have discussed standardizing our style choices for HTML, CSS, and JS, such as 80-character line breaks and 2-space indentation.

Update 27 Jan 2025:

After some experimentation and discussion (below) it is apparent that this touches on many things, and the solution comes in several parts. Some things can be automated (like indentation in HTML and CSS files), and some things will require a style guide or component usage documentation that developers have to interpret and apply manually: like having one h1 per page, or whether or not to use all caps in our designs, or how to use color pairs. A lot of these will be put into a design system when and if we adopt / create one.

Because the automatic bits are lower-hanging fruit and can be implemented more quickly, I'd like to split them off. One that comes to mind is:

• https://github.com/openlibhums/memory-alpha/issues/130

Start by reading the discussion on this issue and the linked issue #130, since the work has been split into automated formatting and broader style or design-system guidance. Clarify which part remains here and define completion criteria before choosing documentation locations or implementation work; no files or tests are named in the issue.