Rotate & Flip elements(images, gifs, videos)

Suggested here: https://github.com/lettucegoblin/pureref-gif-support/issues/2#issue-1980199763

My initial thoughts are:

• Rotate: Use css transform: rotate3d since it's gpu accelerated
• Flip/invert: Possibly use transform: rotate3d.
  • I'm more familiar with rotateY(180deg) inverting over the y axis and rotateX(180deg) for x axis
• Add rotation gimbal to rotate and right click context to flip image over y or x axis.
  • Insane stretch goal is 3d gimbal since rotate3d supports laying things out with perspective. It'd be even more insane to have a toggleable perspective grid that you can snap things to 💯
• Update saving: save rotation state for each element
  • Support older savefiles: Add default neutral rotation state to each element on load if not detected.

Start by tracing how image, GIF, and video elements are rendered and how their state is saved and loaded; the issue does not name specific files or tests. Define the scope before implementation, separating rotation, X/Y flipping, controls, persistence, and older savefile compatibility. Done means these elements can be rotated or flipped and their rotation state survives saving while older savefiles receive a neutral default.