Compress images with oxipng

[hugovk]

Fixes #1518.

See #1514 (comment) for amount of compression.

Also add pre-commit hook, and update README about how to use prek, which is a faster version pre-commit client. And you can use either locally.

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I've not committed the compressed files here, let's see if pre-commit.ci will do it.

[europython-society]

Preview available

Key	Value
url	https://oxipng.ep-preview.click
last update	2026-06-30T07:55:08.276Z

[hugovk]

Hmm, timeout after 180 seconds!

I'll run it locally and push, and see if that makes a difference. Another option is to remove -o=max which should make it quicker, but still compress well.

[hugovk]

Same thing. Let's try without -o=max, locally that speeds it from 2m42s to 11s!

The commit with compression did use -o=max.

[hugovk]

Bingo!

[egeakman]

Thank you so much for implementing this @hugovk! I just realized I forgot to clean up some images from last year (the ones in public), do you mind if we hold this up for now and rebase it after the clean-up?

[hugovk]

Sure, just ping when ready!

[hugovk]

Little reminder about this, it could help for things like #1588 as well :) Was the cleanup done?

[hugovk]

Also converted src/content/sponsors/vercel/display.png from a JPG with a .png extension to a real PNG.

[nikoshell]

I will rebase and merge changes as we have space issues on preview