✨ Preserve reusable functions across jeff import and export

[burgholzer]

🤖 AI text below 🤖

Description

Preserve reusable functions and calls across QCO ↔ jeff conversion using native func.func and func.call conversion patterns. Ordinary calls remain compact; only calls inside quantum modifiers are expanded by the shared modifier pass. Correct the jeff entry-point mapping to index the function table, not the string table.

This PR is rebased on current main, including the jeff-mlir forward-call fix. Imported helpers are private, source function order is preserved, and the entry-point index identifies the original entry function. Classical-register reference arguments remain unsupported and are rejected explicitly.

Codex implemented and tested the changes with an independent jeff/MLIR specialist. The integration reuses existing MLIR conversion and inlining APIs without a new format schema, custom call graph, or whole-program inliner.

Integrated-stack validation: release build; all 3,916 registered CTest cases with one expected skip; all 294 Qiskit translation tests; whole-file C++ lint and repository lint. Stub generation passed without tracked changes. Hosted CI is separate evidence and has not been claimed as passed.

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.
• I have added entries to the changelog for any noteworthy additions, changes, fixes, or removals.
• I have added migration instructions to the upgrade guide (if needed).
• The changes follow the project style guidelines and introduce no new warnings.
• The changes are fully tested and pass the CI checks.
• I have reviewed my own code changes.

If PR contains AI-assisted content:

• Any agent that created, edited, or submitted GitHub content was explicitly authorized for that scope, as required by our AI Usage Guidelines.
• Every agent-authored or agent-edited public text body begins with the visible disclosure 🤖 *AI text below* 🤖 (titles are exempt).
• I have disclosed AI assistance in the PR description.
• I confirm that I have personally reviewed and understood all AI-generated content, and accept full responsibility for it.

[codecov]

Codecov Report

❌ Patch coverage is 95.65217% with 2 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...lir/lib/Dialect/MQT/Transforms/UnrollModifiers.cpp	94.1%	2 Missing ⚠️

📢 Thoughts on this report? Let us know!

[burgholzer]

This feels very clean. I'm merging this for now as I continue through the stack of PRs here.