🎨 Re-sort C++ includes

[denialhaag]

🤖 AI text below 🤖

Apply the include-order rules discussed in #2227 (comment) across the non-vendored C++ sources: matching header, MQT Core headers, other private or third-party headers, MLIR, LLVM, then system and standard-library headers. Use angle brackets only when required.

Encode the order in .clang-format.

Consider an mqt/ prefix to distinguish MQT’s MLIR headers from upstream MLIR headers.

[burgholzer]

I believe the mqt prefix could genuinely make sense as a distinction