Implement bulletsync validation checks across various components

[QueryOfficial]

Summary

Adds server-side bullet sync + weapon aim validation to stop forged or flooded bullet-sync packets from being relayed before main-thread checks run.

• Shared validation in SyncBulletsyncValidation.h — geometry (origin, segment, impact), damage fields, NaN/Inf, degenerate segments
• CBulletsyncPacket, CSimBulletsyncPacket, CCustomWeaponBulletSyncPacket use shared helpers for consistent checks
• CGame::Packet_Bulletsync / Packet_WeaponBulletsync validate before onPlayerWeaponFire and relay
• CSimPlayerManager::HandleBulletSync runs the same validation + rate limit before sim broadcast (fixes early relay crash)
• CPlayer::TryAcceptBulletsync() — max 25 bullet-sync packets / second per player
• Weapon aim validation on puresync/keysync (main + sim thread) to block origin ≈ target crashes
• Client defense-in-depth: CNetAPI::ReadBulletsync, CClientPed::SetTargetTarget
• Docs: Server/mods/deathmatch/README.weapon-sync-guard.md

No netcode protocol changes.

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Motivation

Cheats hook client SendBulletSync and can:

• send many bullet-sync packets per physical shot (DamageDividier loops)
• forge start/end vectors (non-finite, extreme trajectories, wall-shot muzzle offsets)
• crash remote clients before onPlayerWeaponFire fires on the server

Root cause: the sim thread relayed PACKET_ID_PLAYER_BULLETSYNC before main-thread validation. Invalid packets reached nearby clients even when CBulletsyncPacket::Read() later rejected them.

This fix validates geometry and damage on both paths and drops packets before apply/relay. Rate limiting catches multi-packet spam per shot.

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Test plan

Build this branch, use 2+ clients on a private test server.

Normal gameplay

• Fire common weapons (pistol, SMG, sniper) at players/objects — hits, damage, and onPlayerWeaponFire behave as before
• Shoot from vehicle and on foot — no false rejects at normal ranges
• Remote player aim/animation looks correct for nearby observers

Attack regression (requires bullet-sync cheat / test hook)

• Multi-packet spam: Single shot sending 10+ bullet-sync packets → nearby clients not crashed; excess dropped (25/s limit)
• Forged trajectory: Wall-shot / extreme origin offset → packet rejected; no bogus hit on victim
• Sim relay path: Shooter and victim near each other → invalid packets not relayed early by sim thread
• onPlayerWeaponFire: Event fires only for accepted packets; no crash-before-event regression

Expected results

• Cheat bullet-sync spam / forged geometry → blocked on main + sim thread; no remote crash
• Normal weapon fire → unchanged
• onPlayerWeaponFire only for valid, rate-limited packets
• Non-finite or degenerate aim vectors → rejected without client crash

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Checklist

• Your code should follow the coding guidelines.
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