Port Jay Moran's arcade carts: src/arcade #9197

Files: src/arcade/* (carts, cover, host, import, shelf, snapshot, arcade.html). Bring only what runs on main; the shelf is a display, so it waits for displays.

Co-authored-by: Jay Moran on the commits. Source: origin/incoming/jay-main (ebc0adc); take his files whole with git checkout, adapt only the wiring to main, keep his design, add a real test and a preview. Split off #9053; Iterations and build pins are already on main.

No longer waits for #9195: the cycle was the arcade host, shelf and snapshot, which import src/display. This issue is now the carts alone (carts, cover, import and their assets); shelf.ts moves to #9207, and host.ts and snapshot.ts to #9208. #9194 waits for this one, because Jay's pin_demos imports arcade/carts.