e107f5e218
Action buttons sized to text + 8 px padding made "Undo" end up ~46 x 33 px — fine for a mouse but at the threshold of a finger. Adds `min_width: 48 px` and `min_height: 48 px` to the button Node so every button meets Material's 48 dp thumb-target guideline. Applied universally; the floor is a no-op for buttons whose content already exceeds 48 px on either axis (Menu, Modes, New Game, Pause, Help all clear 48 px wide; height was the binding constraint at ~33 px). Closes P1 #2 of docs/android/PLAYABILITY_TODO.md. Engine tests pass; clippy clean. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>