Implement proxy weapon animation sync for ranged guns

Milestone 1: Proxy actors now equip remote players' right-hand weapons and play armed idle/locomotion poses when weaponDrawn=true. Adds rightHand weapon slot to equippedItems protocol, weapon graph variable support (iSyncGunDown: 0=drawn, 1=holstered), and weapon FSM events (weaponDraw, readyStateEnter, gunDownStateEnter). Fixes two critical animation state churn bugs: frustum-visibility flicker no longer resets animation state on every update tick, and idle proxies no longer register as changed on every frame. Includes WeaponBehavior graph loading via AIProcess::RequestLoadAnimationsForWeaponChange() and manual weapon attachment fallback. New docs/weapon-animation-sync.md reference guide maps animation events and variables from F4-Animation-Research. Experimental alert-state reassertion for armed proxies to test NPC combat state gating of weapon-ready poses.

plugin/include/F4TProxyAnimationSync.h

@@ -33,6 +33,9 @@ namespace F4T::ProxyAnimationSync
 		inline constexpr const char* kSyncWalkRun = "iSyncWalkRun";
 		inline constexpr const char* kSyncLocomotionSpeed = "iSyncLocomotionSpeed";
 		inline constexpr const char* kSyncJumpState = "iSyncJumpState";
+		// Weapon animation graph variables (RaiderRootBehavior / WeaponBehavior)
+		inline constexpr const char* kSyncGunDown = "iSyncGunDown";
+		inline constexpr const char* kRifleDrawnStateID = "iRifleDrawnStateID";
 	}
 
 	// MTLocomotionBlend_SM sub-states: Walk(0), Jog(1), Run(2). Selected by graph events