Add Home Page Images

[secondsleep-blaine]

Add images where there are currently placeholders on the home page.

• [x] Main splash needs an image or a better color choice.
• Add images for the following elements.
  • [x] Procedures
  • [x] Explainers
  • [x] Thoughts

[secondsleep-blaine]

I'm no longer using the procedures/explainers/thoughts breakdown the same way, so those subtasks no longer apply.

[secondsleep-blaine]

This is good enough for now, but I'll re-evaluate this later and open a new issue.