Add Full Sphinx Documentation Support with API Autogeneration and CI Integration

[harryswift01]

Summary

This PR introduces full Sphinx documentation support to the project, enabling documentation to be built locally, in CI, and on Read the Docs. It also adds the necessary scaffolding for automatic API documentation generation.

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Changes

Add Sphinx Documentation Structure

• Added docs/ directory with Sphinx setup
• Added Makefile and make.bat for building docs locally
• Added docs/source/conf.py with configuration and extensions (autodoc, autosummary, napoleon, etc.)
• Added docs/source/index.rst as documentation entry point
• Removed old top-level Markdown docs (index.md, installation.md)

Add Documentation Build Support

• Added .readthedocs.yaml to enable Read the Docs builds with Python 3.13
• Configured RTD to install package with extra_requirements: docs
• Updated GitHub Actions workflow to build docs during CI

Automatic API Documentation Support

• Enabled autosummary_generate = True to allow auto API page generation
• Added Sphinx extensions for improved docs experience (viewcode, copybutton, mathjax, intersphinx, nbsphinx, etc.)
• Project is now ready to generate module and API docs via autosummary/autodoc

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Impact

• Documentation builds now work locally, in CI, and on Read the Docs
• Foundation for expandable documentation and tutorials is established
• Automatic API docs are supported once modules are added to a toctree (e.g., via api.rst)
• Improves maintainability and accessibility for future contributors and users