Mark puzzles as screenreader-friendly

[tabascq]

Also, have a filter in the puzzle list that shows only screenreader-friendly puzzles.

This should maybe be an optional event setting, or even better maybe the UX only turns on when at least one puzzle has the flag marked.

[tabascq]

Nate and I feel this is the most impactful thing we can do for accessibility at this point.

Nate adds: "Perhaps even a variation that indicates "this puzzle requires hearing, this puzzle requires fine motion, etc." sort of like how we evaluate the puzzles at a high level."

[vidapour]

start conversations with Jeremy + Nate in January