Add social preview and proper page titles

[TilBlechschmidt]

Duh.

[TilBlechschmidt]

SSR has been fixed so the <svelte:head> tag can now be used to add all the metadata 🙂

Here are some links that help to figure out what to put in there:

• https://css-tricks.com/essential-meta-tags-social-media/
• https://ogp.me

[TilBlechschmidt]

Solved by https://github.com/TilBlechschmidt/ELSA/commit/8d95a5928244501ac5b56b2090b57cb4e256b63e

Note to self: Twitter requires exact image dimensions of 1200x630 for whatever reason.