Report indicator

It definitely would improve quality of life if when you report an image a small indicator appeared to show it. Something like the yellow indicator you have to distinguish web-gen pics vs uploaded ones. A red one on a corner for instance.

The motivation is simple:
- it's easy to get lost when reporting multiple pics due to the uneven tiling of the images
- when refreshing and if new content shows up, the pic order might change.

Knowing what you reported already and what you didn't would prevent things from slipping through the cracks