Add CI for tests and CD for docs deployment

- Added `.github/workflows/ci.yml` to run tests on Python 3.10 and 3.11.
- Added `.github/workflows/deploy-docs.yml` to deploy mkdocs to gh-pages.
- Updated `pyproject.toml` to include `mkdocs-material` dependency.
- Updated `mkdocs.yml` to use `material` theme.
- Added `site/` to `.gitignore`.
- Fixed CI error by removing `submodules: recursive` (broken submodule references).

Author: google-labs-jules[bot]

.github/workflows/ci.yml

@@ -15,8 +15,6 @@ jobs:
 
     steps:
     - uses: actions/checkout@v4
-      with:
-        submodules: recursive
 
     - name: Set up Python ${{ matrix.python-version }}
       uses: actions/setup-python@v5