Add ROS 2 Lyrical Luth (Ubuntu 26.04) support and remove Rolling

[bburda]

Summary

ROS 2 Lyrical Luth was released in May 2026 as the new LTS (supported until May 2031), targeting Ubuntu 26.04 Resolute Raccoon. Swap our Rolling CI matrix entries for Lyrical so we test against a stable LTS instead of a moving target.

Proposed solution

• CI matrix in ci.yml, docker-publish.yml, opcua-plugin.yml: rolling/ubuntu:noble -> lyrical/ubuntu:resolute. Jazzy + Humble entries unchanged.
• ROS2MedkitCompat.cmake: extend docstrings to cover Lyrical (rclcpp 32+, yaml_cpp_vendor target export, ament_target_dependencies removed in ament_cmake 2.8.5+ which Lyrical ships). Runtime detection already handles the new distro; no logic change needed.
• Docs (README, CONTRIBUTING, QUALITY_DECLARATION, installation, troubleshooting, tutorials, copilot-instructions, cmake/gateway design docs): rephrase distro lists from Jazzy/Humble/Rolling to Jazzy/Humble/Lyrical Luth with correct Ubuntu codename pairings (Resolute=26.04, Noble=24.04, Jammy=22.04).
• Source comments (C++ plugin destructors, gateway main, snapshot_capture, scripts, integration tests): swap Rolling -> Lyrical where appropriate; preserve historical attribution where the bug was first observed on Rolling ("on Lyrical (originally observed on Rolling)" / "Rolling/Lyrical").
• snapshot_capture.cpp C++20 aggregate-init comment: update gcc version reference (Rolling/14 -> Lyrical/15).

Additional context

• ROS 2 Lyrical Luth release notes: https://docs.ros.org/en/lyrical/Releases/Release-Lyrical-Luth.html
• Ubuntu 26.04 Resolute Raccoon release: https://canonical.com/blog/canonical-releases-ubuntu-26-04-lts-resolute-raccoon
• Out of scope for this change: pinning ros-tooling/setup-ros@v0.7 to a fixed minor (works today), adding a Pixi feature for Lyrical (depends on a RoboStack Lyrical channel), GCC version contradiction in installation.rst (pre-existing).