⚡ Reduce TT entry size to 8 bytes

[eduherminio]

Elo   | 3.33 +- 5.35 (95%)
SPRT  | 8.0+0.08s Threads=1 Hash=8MB
LLR   | 2.91 (-2.25, 2.89) [-5.00, 0.00]
Games | N: 10016 W: 3147 L: 3051 D: 3818
Penta | [381, 1136, 1902, 1184, 405]
https://openbench.lynx-chess.com/test/21/

Elo   | 0.63 +- 8.95 (95%)
SPRT  | 40.0+0.40s Threads=1 Hash=64MB
LLR   | 0.47 (-2.25, 2.89) [-5.00, 0.00]
Games | N: 3308 W: 951 L: 945 D: 1412
Penta | [98, 395, 660, 405, 96]
https://openbench.lynx-chess.com/test/22/

Elo   | -1.74 +- 12.04 (95%)
SPRT  | 40.0+0.40s Threads=1 Hash=32MB
LLR   | -0.00 (-2.25, 2.89) [-5.00, 0.00]
Games | N: 1800 W: 503 L: 512 D: 785
Penta | [51, 216, 374, 209, 50]
https://openbench.lynx-chess.com/test/23/