Infinite loop in `SkeletonAnimation::PoseAtX` when X-axis displacement is zero

[XINJIANGMO]

Environment

• OS Version: Ubuntu 24.04
• Source or binary build?
  source , gz-common7

Description

• Expected behavior: The function should detect that the animation has no forward (X) displacement and handle it gracefully rather than looping forever.
• Actual behavior: looping forever

Steps to reproduce

1. add a test in SkeletonAnimation_TEST.cc

/////////////////////////////////////////////////
TEST_F(SkeletonAnimation, CheckPoseAtXLooping)
{
  common::SkeletonAnimation skelAnim("testAnimation");
  skelAnim.AddKeyFrame("node1", 1.0, math::Matrix4d::Identity);

  auto pose = skelAnim.PoseAtX(2.0, "node1", true);
  ASSERT_EQ(pose["node1"], math::Matrix4d::Identity);
}

Propose Fix

Fix in SkeletonAnimation.cc
function PoseAtX

if (lastX > 1e-6) {
    while (x > lastX)
        x -= lastX;
} else {
    x = 0; 
}