docs: migrate to Zensical for documentation

[0x676e67]

close: #522

[gemini-code-assist]

Code Review

This pull request performs a significant overhaul of the project's documentation, including a transition to zensical for builds, a complete restructuring of the navigation menu, and the addition of detailed guides and a comprehensive introduction page. It also includes minor code cleanups and the addition of ellipses to stub methods in the Python source files. Feedback identifies a critical syntax error in the .readthedocs.yaml configuration that would likely break the documentation build and a copy-paste error in a badge URL within the new introduction file.