Add OpenGraph image generation crate

[Turbo87]

This PR adds a new crates_io_og_image crate that generates OpenGraph images for crates.io packages using the Typst typesetting system.

Features

• Generates 1200x630px images with crate metadata (name, description, version, license, tags, metrics)
• Downloads and renders author avatars from URLs
• Handles text truncation and overflow for long content
• Uses Typst typesetting system for layout and rendering
• Uses snapshot tests for visual regression detection

(more screenshots available in the snapshots folder in the diff view 😉)

The generated images are used for social media previews when crates.io links are shared.

Note that the crate is not integrated into the main crates.io application yet. This will be done in a follow-up pull request.

[Turbo87]

hmmmmm..... looks like the PNG snapshot tests aren't quite as portable as I had hoped... 😅

[Turbo87]

hmmmmm..... looks like the PNG snapshot tests aren't quite as portable as I had hoped... 😅

I take that back. The issue was caused by the CI machines not having the Fira Sans font pre-installed. I've added that to the CI workflow now and it seems that CI is happy with it 🎉

[saharshxyz]

Great new edition using modern tooling – love to see it! Having fun talking about this in the Typst discord :)

[NiklasEi]

Typst's PNG export is (understandably) optimized for speed and not file size. If I understand the plan correctly, the images will be rendered once and then cached. So it would probably be worth it to run something like oxipng over the results, trading a bit more time for a reduction in file size.

A quick test with the output of the example from this PR => 56% smaller file size.

time oxipng -o 2 --strip safe test_og_image.png 
Processing: test_og_image.png
55478 bytes (56.00% smaller): test_og_image.png

real	0m0.136s
user	0m0.130s
sys	0m0.042s

time oxipng -o 4 --strip safe test_og_image.png 
Processing: test_og_image.png
53965 bytes (57.20% smaller): test_og_image.png

real	0m0.325s
user	0m0.948s
sys	0m0.028s

I hope this is the right place for a comment like that. I really like the idea of this PR!

[Turbo87]

I hope this is the right place for a comment like that

absolutely. that's a great idea, thanks! :)