Migrate docs to MkDocs with Material theme

Replaces Sphinx with MkDocs, adopting the Material theme for documentation.

Updates CI workflows and invoke tasks for MkDocs commands.
Converts 73 RST files to Markdown and removes RST directives from Python docstrings.

Enhances API documentation using mkdocstrings to parse NumPy-style docstrings.

Author: jf---

CHANGELOG.md

@@ -9,10 +9,19 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+- MkDocs + Material theme based docs
+
 ### Changed
 
+- update CI workflow for mkdocs gh-deploy
+- update invoke tasks for mkdocs commands
+
 ### Removed
 
+- replace Sphinx with MkDocs + Material theme
+- use mkdocstrings for API docs from NumPy docstrings
+- convert 73 RST files to Markdown
+- remove RST directives from Python docstrings
 
 ## [2.15.0] 2025-11-12