Fix 64-bit portability issues

[bobmoser76]

Summary:

• remove 32-bit assumptions from math bit operations and random seeds
• make PVS word operations and script VM stack slots safe on 64-bit targets
• index lexer punctuation tables with unsigned bytes

Validation:

• fresh Meson debug build with the native Linux platform backend
• client, dedicated server, and unified game module linked successfully
• git diff --check