Reimplement host synchronization checks and periodic messages

[Krarilotus]

Reimplements how the host decides that players have gone out of sync and when the game sends its regular synchronization messages. It also adds the unit-buffer hash helper, providing tested C++ counterparts for three native routines used in network and replay investigations.

• checkGameSync waits for usable samples from participating peers and compares hashes only at equal advertised match times. It preserves the global host/queue receiver, per-instance state, command54, countdown/delay behavior and acknowledgement resets.
• sendPeriodicSyncMessages preserves the signed wrapping clock comparisons: packet126 after more than1800ms, the other sync message at180ms, and countdown updates after the send callback.
• computeSomeHashOnUnitArray delegates the full unit array to the existing hash resolver. It is distinct from the canonical per-domain multiplayer hash calculation.

Validation:

• Normal full OpenSHC.dll CMake build passed, using MSVC2005 SP1 and a Microsoft-signed Windows SDK manifest tool. The older bundled manifest tool crashes on this machine. No DLL was deployed.
• All 397 +91 +21 function bytes match the original Crusader after binding native resolver addresses. Verified address/layout translation also matches the three original Extreme routines; this is not an Extreme OpenSHC DLL build.
• 9,380 differential x86 cases passed, including peer/time/hash gates, independent receiver/global objects, timer boundaries/wrap, callback mutation, delegated hash arguments/return values, memory writes and ABI. The clock, message delivery and delegated hash are controlled boundaries; transport and full-world hash generation are not exercised.
• Linked reccmp scores: host check 98.02%, periodic sends 92.59%, unit-buffer helper 60.00%. These reflect the actual linked resolver/symbol differences and are separate from native-bound byte matches.
• Reproducible validation scripts and their boundaries are included in tools/validation/README.md.

Based on upstream main; existing generated headers and activation flags are unchanged. This does not finish resynchronization, fix the observed TCP hosting hang, or enable multiplayer replay. It complements #222's synchronization command implementation.