docs: standardize Jazzy and Python 3.12 guidance

[Xuwznln]

Summary

• add a canonical runtime/ABI baseline for Python 3.12.13, ROS 2 Jazzy, NumPy 2, and mutex 0.15
• add migration guidance for legacy Python 3.11 / ROS 2 Humble environments
• link the baseline from both READMEs, the docs index, installation guide, and best-practice guide
• update the external device-package template to Python 3.12.13 and robostack-jazzy
• standardize installation commands on the uni-lab, conda-forge, and robostack-jazzy channels
• retain the Humble recipe only as explicitly documented legacy compatibility
• repair three pre-existing broken documentation links and add the missing Sphinx static directory

Validation

• all 32 Markdown files pass local relative-link validation
• git diff --check passes
• changed Python comment/docstring files pass py_compile
• Jazzy/Python 3.12 documentation build (no Pages deployment): https://github.com/deepmodeling/Uni-Lab-OS/actions/runs/31347100256