Update Makefile doc target to run doctest then html builders

[Copilot]

Updates the doc target in the Makefile to run both the doctest and html sphinx builders sequentially, as requested in the issue.

Changes Made

The doc target now executes two sphinx-build commands:

1. First: Runs the doctest builder to validate code examples in documentation
2. Second: Runs the html builder to generate the HTML documentation

doc:
	uv run --no-sync sphinx-build -M doctest docs/source docs/build/ -W --keep-going --fresh-env
	uv run --no-sync sphinx-build -M html docs/source docs/build/ -W --keep-going --fresh-env

Both commands use the same arguments (-W --keep-going --fresh-env) to ensure consistent behavior and error handling.

Benefits

• Documentation Quality: Doctest validation ensures code examples in the documentation are correct and up-to-date
• CI/CD Integration: Both validation and generation happen in a single make doc command
• Consistency: Maintains the same sphinx-build arguments for both builders

Testing

• ✅ Verified the updated target runs both builders successfully
• ✅ Confirmed all other Makefile targets remain unchanged and functional
• ✅ Tested with make doctest which depends on the doc target
• ✅ All existing tests continue to pass

This is a minimal, surgical change that adds doctest validation to the documentation build process without affecting any other functionality.