Use Hugo Pipes for CSS/JS assets

[delroth]

Poison currently ships JS/CSS files as statics instead of using Hugo's assets system ("Hugo Pipes", https://gohugo.io/hugo-pipes/). This has several drawbacks (sorted in my relative order of importance, most important first):

• Caching is annoying: asset filenames don't change when modified, so the browser might keep them cached and not reflect changes to the CSS or JavaScript.
• Assets aren't minified: the big vendored libs (e.g. KaTeX) are, but everything else that is custom written in this theme doesn't get minified or optimized.
• Assets aren't bundled: the 5+ JS and 5+ CSS files all need individual HTTP requests to load. This is less important in a HTTP/2 or HTTP/3 deployment, but on HTTP/1.1 it might slow page loads.

This PR migrates to Hugo Pipes and bundles/minifies CSS and JS at build time as much as possible. This moves a bunch of files around, but ultimately the required changes are pretty small, see layouts/** for the actually meaningful stuff.

You can see the results on my website: https://delroth.net/ which is currently running with my fork and includes this PR.

[delroth]

One thing to note: this does require theme users to move their CSS/JS overrides from static/{css,js}/* to assets/{css,js}/* to continue working. I don't know how you want to handle this kind of backwards-compatibility breaking changes in this project, please let me know if you want me to do anything in that regards!

[delroth]

Pagespeed results using this PR (+ a few other minor fixes that don't impact performance): https://pagespeed.web.dev/analysis/https-delroth-net/0wpg4jfttx?form_factor=desktop

[lukeorth]

Thank you, @delroth -- this is fantastic!

Bundling/minifying static assets has been on my to-do list for awhile. It's something that I knew needed to get done, but I hadn't read enough of the Hugo docs to get it working. This PR solves that, so thank you. :slightly_smiling_face:

[lukeorth]

One thing to note: this does require theme users to move their CSS/JS overrides from static/{css,js}/* to assets/{css,js}/* to continue working. I don't know how you want to handle this kind of backwards-compatibility breaking changes in this project, please let me know if you want me to do anything in that regards!

Regarding this, I plan to update the instructions for including custom CSS in the README. It will probably cause some confusion for those affected (at least initially), but the fix is simple enough that I think it can be highlighted in the docs without too much trouble.

Thank you for the heads up!