Fix numerical precision issues in quaternion to RPY conversion

[roman-y-wu]

Description

Fixes #796 Addresses numerical precision errors that occur during quaternion-to-matrix conversion, particularly near gimbal lock singularities. When matrix elements contain small numerical errors (around 1e-12), the atan2 function can return incorrect angles, such as 45° instead of 0° for roll values.

Changes:

• Add epsilon thresholding (1e-10) to matrix elements before RPY computation
• Improve singularity detection to handle near-singular cases
• Add safety checks to prevent division by near-zero cosine values
• Protect atan2 calls when both arguments are very small
• Apply fixes to both Matrix3x3::getEulerYPR() and tf2::impl utilities
• Update .gitignore with comprehensive build and temporary file patterns

This resolves issues where tf2_echo and other tf2 tools would report incorrect RPY angles due to floating-point precision limitations.

Is this user-facing behavior change?

1. tf2_echo users will now see correct RPY values instead of erroneous ones when dealing with quaternions that have numerical precision issues - Before: RPY (degree) [45.000, -90.000, 0.000] (incorrect) - After: RPY (degree) [0.000, -90.000, 0.000] (correct)
2. Any application using tf2 RPY conversion will get more accurate results, particularly: - Near gimbal lock singularities - When quaternions come from tf2 lookupTransform operations - When dealing with transformations that should have zero roll/yaw but show small numerical errors

Did you use Generative AI?

No.

Additional Information

[ahcorde]

Pulls: ros2/geometry2#811 Gist: https://gist.githubusercontent.com/ahcorde/33090dcbff2ef34c0b140b75f1cfc92f/raw/c57298dfab2ca5949d666f30dc274921a4c69b78/ros2.repos BUILD args: --packages-above-and-dependencies test_tf2 tf2 TEST args: --packages-above test_tf2 tf2 ROS Distro: rolling Job: ci_launcher ci_launcher ran: https://ci.ros2.org/job/ci_launcher/16733

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