[PianoNic]

Summary

• Lernendenausweis: the card fills the height left on the page and drags on it scroll the card, so all of it can be reached. Before, it sat in a box of 62 % of the screen height and the page took every drag, so the rest of the card was out of reach.
• Spinners: FCircularProgress draws a 20 px icon by default; in the 14 px box next to "As of" and the 12 px one on the profile picture while uploading it overflowed to one side and turned about the box centre. The icon is now the size of its box.
• Schools sheet: a school with a profile picture shows its logo in the top-left half and the picture in the bottom-right half, cut from top right to bottom left, in the same 40 px circle. Without a picture it shows the logo in the rounded square as before. Schools & accounts is unchanged.
• The fake API serves a made-up student ID card, two more schools for the Schools sheet (EXTRAS=1), and SLOW=<ms> holds back the card and the picture upload to see the spinners.

Closes #607