🚨 Fix new warnings revealed by clang-tidy 18

[burgholzer]

Description

This PR aims to fix all the new warnings that were introduced in clang-tidy versions 18, which have been enabled with the switch to the [email protected].

The first commit, which should later be reverted, just triggers a full clang-tidy run on the whole codebase.

Checklist:

• The pull request only contains commits that are related to it.
• I have added appropriate tests and documentation.
• I have made sure that all CI jobs on GitHub pass.
• The pull request introduces no new warnings and follows the project's style guidelines.

[github-actions]

Cpp-Linter Report ⚠️

Some files did not pass the configured checks!

clang-tidy reports: 1 concern(s)

• include/mqt-core/python/pybind11.hpp:5:10: error: [clang-diagnostic-error]

  'pybind11/pybind11.h' file not found

      5 | #include <pybind11/pybind11.h> // IWYU pragma: export
        |          ^~~~~~~~~~~~~~~~~~~~~

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[codecov]

Codecov Report

Attention: Patch coverage is 96.66667% with 2 lines in your changes missing coverage. Please review.

Project coverage is 91.5%. Comparing base (9e0be09) to head (f63d3f8).
Report is 108 commits behind head on main.

Files with missing lines	Patch %	Lines
include/mqt-core/dd/statistics/Statistics.hpp	50.0%	1 Missing ⚠️
src/algorithms/GoogleRandomCircuitSampling.cpp	0.0%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##            main    #611     +/-   ##
=======================================
- Coverage   91.5%   91.5%   -0.1%     
=======================================
  Files        145     145             
  Lines      14591   14596      +5     
  Branches    2341    2343      +2     
=======================================
+ Hits       13364   13367      +3     
- Misses      1227    1229      +2     

Flag	Coverage Δ
cpp	91.3% <96.6%> (-0.1%)	⬇️
python	99.7% <ø> (ø)

Files with missing lines	Coverage Δ
include/mqt-core/Permutation.hpp	100.0% <100.0%> (ø)
include/mqt-core/QuantumComputation.hpp	92.3% <100.0%> (-0.2%)	⬇️
...qt-core/algorithms/GoogleRandomCircuitSampling.hpp	58.3% <ø> (ø)
...e/mqt-core/datastructures/DirectedAcyclicGraph.hpp	94.5% <ø> (ø)
include/mqt-core/datastructures/DirectedGraph.hpp	89.0% <100.0%> (+0.2%)	⬆️
include/mqt-core/datastructures/DisjointSet.hpp	100.0% <ø> (ø)
include/mqt-core/datastructures/Layer.hpp	89.1% <ø> (ø)
...nclude/mqt-core/datastructures/UndirectedGraph.hpp	90.7% <ø> (ø)
include/mqt-core/dd/Benchmark.hpp	87.5% <100.0%> (+1.7%)	⬆️
include/mqt-core/dd/CachedEdge.hpp	84.2% <ø> (ø)
... and 107 more

[burgholzer]

The missing pybind11 include is inevitable in the current setup. Continuing to merge.