Fix camera recoil system overriding all other eye offsets (#29146)

Content.Shared/Camera/GetEyeOffsetEvent.cs

@@ -0,0 +1,19 @@
+using System.Numerics;
+using Content.Shared.Movement.Systems;
+
+namespace Content.Shared.Camera;
+
+/// <summary>
+///     Raised directed by-ref when <see cref="SharedContentEyeSystem.UpdateEyeOffset"/> is called.
+///     Should be subscribed to by any systems that want to modify an entity's eye offset,
+///     so that they do not override each other.
+/// </summary>
+/// <param name="Offset">
+///     The total offset to apply.
+/// </param>
+/// <remarks>
+///     Note that in most cases <see cref="Offset"/> should be incremented or decremented by subscribers, not set.
+///     Otherwise, any offsets applied by previous subscribing systems will be overridden.
+/// </remarks>
+[ByRefEvent]
+public record struct GetEyeOffsetEvent(Vector2 Offset);