Add ros2 package names to the Rolling page

[mini-1235]

Summary

• include canonical ros2-* artifacts on the Rolling package page while retaining legacy ros-rolling-* compatibility packages
• store and display exact Conda artifact names without changing Humble, Jazzy, Kilted, or Lyrical naming
• recommend ros2-* in Rolling installation examples

Validation

• pixi run lint
• pixi run build-docs
• pixi run python scripts/compare_pkg_completeness.py rolling https://prefix.dev/robostack-rolling
• verified generated non-Rolling pages contain no ros2-* package instructions
• git diff --check

[mini-1235]

I have only applied this pattern to Rolling for now. I assume we don't want to apply it to the other distros yet.