Fix Include Dependencies and Standardize Formatting

[MitchellThompkins]

Overview

This PR resolves build failures caused by alphabetical include reordering. It ensures all headers are self-contained and standardizes the project's code style.

Key Changes

• Header Integrity: Fixed missing internal dependencies in math/complex.hpp, matrix/matrix.hpp, and all decomposition headers. They now explicitly include the math utilities they require.
• Tooling:
  • Enabled SortIncludes: true in .clang-format.
  • Added make check-format to the Makefile.
  • Integrated a formatting check into the GitHub Actions CI pipeline.
• Standardization: Applied a consistent C++17 formatting style across the entire codebase