Remove ReadTheDocs integration from climakitae

[neilSchroeder]

Summary of changes and related issue

This PR removes ReadTheDocs from the climakitae repository and consolidates documentation around MkDocs/GitHub-hosted docs.

Changes included:

• Removed ReadTheDocs config file: .readthedocs.yaml
• Updated project metadata docs URL in pyproject.toml to GitHub Pages
• Replaced ReadTheDocs links in project docs/readmes with non-RTD equivalents
• Updated MkDocs inventory URL for Dask to a non-RTD endpoint
• Removed legacy Sphinx docs tree under docs/ and associated Sphinx requirements files

Related issue: AE-1556

Link to corresponding Jira ticket(s)

https://eaglerockanalytics.atlassian.net/browse/AE-1556

Testing

• Unit tests written for new/modified code (goal: 80% coverage)
  • All public functions have unit tests
  • Functions that must produce specific values have unit tests
• Verified that notebooks utilizing affected functions still work
• Appropriate manual testing completed
• Advanced Testing label added to PR if this PR makes major changes to the codebase

How to Test

1. Check out branch docs/remove-readthedocs.
2. Confirm no ReadTheDocs references remain in tracked files:
   • git grep -n "readthedocs"
   • Expected result: no matches.
3. Confirm RTD config is removed:
   • test ! -f .readthedocs.yaml && echo "removed"
4. Verify docs metadata and links:
   • pyproject.toml points Documentation to https://cal-adapt.github.io/climakitae/dev/
   • README.md contributing/docs links no longer point to climakitae.readthedocs.io
5. Optional: run docs build sanity check:
   • mkdocs build

Documentation

• Complex code includes comments explaining logic
• NumPy-style docstrings added/updated for all new or modified public functions, classes, and modules

Which of the following need updating? Check all that apply and complete them:

• Concept / architecture docs (docs-mkdocs/climate-data-interface/) — update if you changed how a processor, validator, or data access component works
• MAINTAINERS.md — update release notes, secrets inventory, or CI table if you changed workflows or infrastructure

Code Quality

• Follows PEP8 naming and style conventions
• Helper functions prefixed with underscore _
• Linting completed and all issues resolved
• Does not replicate existing functionality
• Aligns with general coding standards of existing codebase
• Code generalized for multiple uses (unless too complex/time-intensive)

Review Process

• PR review instructions provided:
  • Type of review requested (scientific/technical/debugging)
  • Level of review detail needed

Requested review type: technical/docs + repository hygiene.
Requested review detail: medium; focus on link correctness, removal completeness, and whether deleting legacy docs/ is acceptable for current docs strategy.

Administrative Reminders

• Jira ticket moved to "Review" when PR created
• Jira ticket will be moved to "Done" when complete
• PR branch will be deleted after merge

[acordonez]

Test steps 1-4 all worked as expected. Can't find any readthedocs references in this branch.
Optional step 5 is throwing the same error as the last documentation PR, so I have not checked that:

Error: MkDocs encountered an error parsing the configuration file: while constructing a Python object
cannot find module 'pymdownx.superfences' (No module named 'pymdownx')
  in "/Users/anaordonez/Documents/Code/climakitae/mkdocs.yml", line 88, column 19

[claalmve]

Test steps 1-4 all worked as expected. Can't find any readthedocs references in this branch. Optional step 5 is throwing the same error as the last documentation PR, so I have not checked that:

Error: MkDocs encountered an error parsing the configuration file: while constructing a Python object
cannot find module 'pymdownx.superfences' (No module named 'pymdownx')
  in "/Users/anaordonez/Documents/Code/climakitae/mkdocs.yml", line 88, column 19

Ditto, otherwise LGTM