Add transition to accordion component

[Hoppi164]

This PR adds a transition to the accordion component when expanding or collapsing.
This solution uses only CSS

Note: the interpolate-size css property is required to make this work.
The interpolate-size property is experimental with ~70% global browser adoption.

for this reason i've also added a fallback solution to transition the margin-bottom of the summary element which fakes a similar effect.

Screencast.from.2025-06-20.20-39-34.mp4

Inspired by this stack overflow answer:

https://stackoverflow.com/questions/38213329/how-to-add-css3-transition-with-html5-details-summary-tag-reveal#Toggle%20details%20height%20from

[Hoppi164]

@lucaslarroche

Feel free to make any adjustments you deem necessary,
alternatively please let me know if you need me to change anything.

Love your work mate
I use Pico CSS on all my personal projects
<3