Add first-person camera mode with pose-aware eye offset and yaw facing

Introduce a FirstPersonController / FirstPersonMode pair (mirroring the
free-cam mode) wired into the GameModeManager Tab cycle. In first person the
mesh is hidden, the eye sits on CameraTarget plus a per-pose
firstPersonCameraTargetYOffset, and the character body yaw is driven to match
the camera via a new single-writer FaceYaw hook on PlayerCharacterController.

Also includes user content edits (poses, prefabs, scene) carried along.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Assets/Scripts/PlayerPoseController.cs

@@ -95,6 +95,7 @@ public partial class PlayerPoseController : MonoBehaviour
     private bool _blending;
 
     private float _cameraPoseOffset;      // eased per-pose camera-target offset routed to the controller's camera target
+    private float _firstPersonCameraOffset; // eased per-pose first-person eye offset, read by the FirstPersonController (never written to the shared camera target)
 
     // Capsule blend: the CharacterController dimensions are eased toward the active pose's via a single
     // normalized blend (so the capsule stays a valid shape throughout) and written through the controller.
@@ -120,6 +121,9 @@ public partial class PlayerPoseController : MonoBehaviour
     /// <summary>Index of the currently selected pose.</summary>
     public int CurrentIndex => _currentIndex;
 
+    /// <summary>Eased per-pose y-offset for the first-person eye, applied on top of the camera target by the FirstPersonController.</summary>
+    public float FirstPersonCameraYOffset => _firstPersonCameraOffset;
+
     void Awake()
     {
         _player = GetComponent<PlayerCharacterController>();
@@ -178,6 +182,14 @@ public partial class PlayerPoseController : MonoBehaviour
             ? Mathf.MoveTowards(_cameraPoseOffset, cameraPoseTarget, cameraOffsetSpeed * Time.deltaTime)
             : cameraPoseTarget;
         _player.SetCameraTargetLocalYOffset(_cameraPoseOffset);
+
+        // First-person eye: a separate per-pose offset, eased the same way but NOT routed to the shared
+        // camera target (that would also move the ThirdPersonCamera). The FirstPersonController reads this
+        // and applies it to its own eye position only.
+        float firstPersonTarget = pose ? pose.FirstPersonCameraTargetYOffset : 0f;
+        _firstPersonCameraOffset = cameraOffsetSpeed > 0f
+            ? Mathf.MoveTowards(_firstPersonCameraOffset, firstPersonTarget, cameraOffsetSpeed * Time.deltaTime)
+            : firstPersonTarget;
     }
 
     void OnDisable()
@@ -186,6 +198,7 @@ public partial class PlayerPoseController : MonoBehaviour
         // next idle frame. Also clear the camera offset and restore the default capsule we were holding.
         ReleasePose();
         _cameraPoseOffset = 0f;
+        _firstPersonCameraOffset = 0f;
         if (_player)
         {
             _player.SetCameraTargetLocalYOffset(0f);