OverworldLoop (home/overworld.asm) jumps straight to .moveAhead while
wWalkCounter is nonzero: JoypadOverworld -- the START check, the A
check, and direction initiation -- only ever runs while the player
stands on a tile, and a button pressed mid-step is simply never seen.
The port ran handleInput() every frame regardless, so a mid-step
A/START pushed its TextBox/StartMenu right there and froze Red between
tiles, mid-animation (the Nurse Joy run-up in the report).
Gate handleInput on player.moving like the original. The port-invented
wall-bonk SFX cooldown is hoisted above the gate so it keeps ticking on
held-direction frames mid-step exactly as before.
Adds tests/parity_midstep_buttons.lua: mid-step and last-frame A/START
presses are swallowed and the step completes, and both buttons work
again once the player stands on the tile.