Guides improvements

In `/guides`, we could add a few improvements:

- [ ] Add pagination
- [ ] Add a creation timestamp field to each guide and order `/guides` by that field (descending). Maybe we should show it in each card too?

In `guides/[guide-slug]`:

- [ ] Consider adding some images to complement the text. Not sure how much effort this would take, but we should give it a simple try and evaluate
- [ ] Add a header image for each guide. We could try generating something similar to the current thumbnail (made with Gemini), though it might not be easy. If not feasible, a different image is totally fine.
- [ ] Polish the titles (h1, h2, h3..) styles and spacing to make the guides feel less like READMEs and more like articles or blog posts. Any other style tweak is welcome 🙏
- [ ] Maybe we should show the creation date?
- [ ] Improve overall formatting/styling of the page. Maybe Andrea / Hunter can do a pass
- [ ] Add code highlighting on code blocks
- [ ] Fix image padding, looks weird on mobile. See example:

https://user-images.githubusercontent.com/12072395/205343533-7e3a2cfe-8329-42af-a35d-6352a12bf61e.png

Start by reading the `/guides` listing and `guides/[guide-slug]` page entry points, then inspect how guide metadata, thumbnails, images, and code blocks are currently rendered. The issue bundles pagination, dates, imagery, typography, mobile spacing, formatting, and syntax highlighting, so define a smaller scoped outcome before starting. Done should be verified against the selected checklist items on both the listing and guide pages, including the supplied mobile image example.

Written by the indexing model from the issue text.