reduce image size

[shenef]

Reduces image size by getting compressed and smaller images from scryfall.
Unfortunately i can't test locally at the moment but all changed links are working.
Potential problems with this change:
The corners of the jpgs are not transparent, might clip the borders around the card and would be visible if a dark theme is added or a dark background is forced.

Closes #172

[glacials]

I cloned this locally and it seems to work great! And image size is reduced by ~10x! 🚀

I totally agree these should be the images loaded by default on the website, however in the API I'd love to continue to include full resolution for when consumers need it. e.g. in the mobile app you can fullscreen a card image by tapping on it, and I'd want that fullscreened version to gracefully try to switch to a full resolution image.

What would you think about deprecating this field and returning all possible Scryfall image URLs, so the consumer can pick? Something like

  "card_image": {
    "small": "https://img.scryfall.com/cards/small/front/7/c/7c77a6b1-ef06-4da5-8e86-a5204216cb77.jpg",
    "normal": "https://img.scryfall.com/cards/normal/front/7/c/7c77a6b1-ef06-4da5-8e86-a5204216cb77.jpg",
    "large": "https://img.scryfall.com/cards/large/front/7/c/7c77a6b1-ef06-4da5-8e86-a5204216cb77.jpg",
    "art_crop": "https://img.scryfall.com/cards/art_crop/front/7/c/7c77a6b1-ef06-4da5-8e86-a5204216cb77.jpg",
    "border_crop": "https://img.scryfall.com/cards/border_crop/front/7/c/7c77a6b1-ef06-4da5-8e86-a5204216cb77.jpg",
    "png": "https://img.scryfall.com/cards/png/front/7/c/7c77a6b1-ef06-4da5-8e86-a5204216cb77.png",
  }

[glacials]

Closing due to inactivity, but feel free to reopen if updated.