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/PlayerCharacterController.cs

@@ -147,6 +147,13 @@ public partial class PlayerCharacterController : MonoBehaviour
     /// </summary>
     public bool ControlEnabled { get; set; } = true;
 
+    /// <summary>
+    /// When set, the body faces this world-space yaw (degrees) every frame instead of turning toward its
+    /// movement direction. First-person sets it so the character always faces where the camera looks;
+    /// null restores movement-facing. Only affects ground/air locomotion — wall-climb owns its own facing.
+    /// </summary>
+    public float? FaceYaw { get; set; }
+
     /// <summary>True while in wall-climb mode.</summary>
     public bool IsWallClimbing => _isWallClimbing;
 
@@ -425,8 +432,13 @@ public partial class PlayerCharacterController : MonoBehaviour
         if (!_groundNormalUpdated)
             _groundNormal = Vector3.up;
 
-        // Face the movement direction, unless the right-button turn is actively steering the body.
-        if (rotateTowardMovement && !groundYawDrag && moveDir.sqrMagnitude > 0.0001f)
+        // Facing: first-person pins the body to the camera yaw (even while idle); otherwise turn toward
+        // the movement direction, unless the right-button turn is actively steering the body.
+        if (FaceYaw.HasValue)
+        {
+            transform.rotation = Quaternion.Euler(0f, FaceYaw.Value, 0f);
+        }
+        else if (rotateTowardMovement && !groundYawDrag && moveDir.sqrMagnitude > 0.0001f)
         {
             Quaternion target = Quaternion.LookRotation(moveDir, Vector3.up);
             transform.rotation = Quaternion.RotateTowards(