Implement a hero animation for the podcast tile

[illright]

A hero animation is when you click on a podcast tile that contains an image, and that image grows in size and moves to the place where that image will be located on the next page. Basically, it's a fancy smooth page transition animation

Acceptance criteria:

• clicking a podcast tile should trigger the page transition (already does)
• the cover art of the podcast should smoothly scale and translate into the place of the cover art in the Podcast Episodes page

Note: no need for such a transition backwards (i.e. from Podcast Episodes to Podcast Gallery), but if it's easy to implement then by all means go for it

[illright]

Sorry, I lied, it's actually called a "Shared Element Transition". Apparently we have an open bug in SvelteKit, sveltejs/kit#628, that references duplication of page content. Generally, from the looks of it, transitions like that are not too easy to implement in a generic, non-fragile way, so maybe we should just close this issue and the linked PR.