Stabilize hand arrangement

[bglw]

• Currently the hand in the UI can somewhat shuffle, which can be offputting
• If you have multiple of the same letter in your hand, you don't have control over which one is played (i.e. the E in the 2nd slot vs the E in the 6th slot).

Truncate moves should change to be slot based, so you play slot 5 at position X, rather than playing letter E.