🐛 Fix Windows diagnostics and device exports

[burgholzer]

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Description

Fix the independent Core diagnostics exposed by the Windows ARM64 release build. This PR is based directly on main and does not depend on #2715 or #2545.

• Use the declared QDMI exports for hidden device libraries. This avoids CMake's automatic export scanner, which fails on MSVC IPO objects before linking; other libraries retain their existing export policy.
• Keep Core's MSVC exception handling and SDK-compatible RTTI flags consistent, including object-library targets, and explicitly pair the benchmark's LLVM EH/RTTI requirements.
• Replace deprecated LLVM APIs and implicit jeff operation conversions, propagate bytecode-writing failures, use std::ignore for deliberately discarded values, and check fallible test setup. Use fixed-width types for DD bit positions and SHA-256 padding bytes.
• Complete the test enum switch and scope the Cap’n Proto/LLVM warning suppressions to the affected dependency target and includes.
• Reject OpenQASM register slices used as Boolean conditions. The missing switch case previously accepted them silently; one case extends the existing regression table.

The QIR C4297 warnings concern exceptions crossing the C entry points and remain part of #2545. The remaining warnings identified in the Windows ARM64 follow-up log are addressed here. No LTO or deployment policy changes are included.

Validation: native Release build; 3,952 tests passed and one expected skip; repository lint; whole-file C++ lint on the changed files. The added OpenQASM case fails before the fix and passes afterward. Focused CMake probes check the actual target helpers with MSVC/native and RTTI configurations, and both device libraries expose all 19 declared QDMI entry points. The Windows ARM64 build passed before the follow-up warning fixes; the latest changes still need MSVC CI validation.

AI assistance: Codex implemented these changes and specialist agents reviewed the MSVC flag and export handling.

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 94.87179% with 2 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
.../Dialect/QC/Translation/TranslateQCToOpenQASM3.cpp	0.0%	1 Missing ⚠️
mlir/tools/mqt-cc/mqt-cc.cpp	50.0%	1 Missing ⚠️

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