✨ Add W-state preparation benchmark

[burgholzer]

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Description

Stacked on #2545.

Add W-state preparation to the existing C++, Python, and CLI benchmark interfaces. The generator keeps its controlled-RY/CX sweep in structured loops with precomputed angles. Evaluation reuses the existing probability and counts APIs: each single-excitation outcome has ideal probability 1/n.

The 4,096-qubit regression checks jeff serialization, reload, and amplitudes through the existing DD simulator without dense extraction. Supporting large preparations raises the shared control-flow budget to 100 million steps and rejects oversized resolved loops before execution. Documentation includes executable 3- and 256-qubit examples.

Validation:

• Optimized native build; 66 benchmark, 33 generation, and 196 QCO utility tests; benchmark CLI CTest.
• 199 focused Python tests and regenerated stubs.
• Full-file C++ lint against the base branch, repository lint, and complete executable documentation with local link checks.

Hosted checks will rerun on this update. Codex assisted implementation, validation, and this description.

Checklist

• The pull request only contains commits that are focused and relevant to this change.
• I have added appropriate tests that cover the new/changed functionality.
• I have updated the documentation to reflect these changes.
• The changes follow the project's style guidelines and introduce no new warnings.
• The changes are fully tested and pass the CI checks.
• I have reviewed my own code changes.

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[codecov]

Codecov Report

❌ Patch coverage is 93.22034% with 4 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
mlir/lib/Dialect/QCO/Utils/DDFunctionality.cpp	33.3%	2 Missing ⚠️
src/bench/JSON.cpp	86.6%	2 Missing ⚠️

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