Both games now render at 60 fps independent of the game-logic step rate:
the main loop caps select() at one frame (16 ms) so the screen updates
smoothly even when gravity/snake steps are slow, and renders every frame
or whenever state changed.
Snake: replaced the turn queue with a single buffered direction (latest
keypress wins) so rapid key presses don't queue up and misfire. Base speed
set to 100 px/sec (~90 ms per step) for controllable, responsive play.
Progressive difficulty (+1 px/sec per 5 food) and edge wrap are unchanged.