Implement the ability for covers to be blurred if they are NSFW

[majora2007]

This can be either a library setting or a user setting, need to do some testing on what is a better experience. Based on the age rating for the series, the cover image will have some sort of censoring on it.

Ideal: Blur Acceptable: Swap out for some placeholder image?

[majora2007]

Perhaps blur (or swap image) based on Series rating (as most people don't tag all chapters unless comics).

[majora2007]

filter: blur(5px); works perfectly on the cards to apply a blur.