🚚 Move DD sampling to MQT DDSIM

[simon1hofmann]

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Description

Move the DD sampling used by the CSP and TSP solvers from mqt.core.dd to
mqt.ddsim, where the high-level simulator API is moving as part of
munich-quantum-toolkit/core#2103.

ProblemSolver now requires Python 3.11 after #528, so this branch imports
sample from DDSIM unconditionally and adds mqt.ddsim>=2.6.0. No
ProblemSolver API or solver behavior is intended to change.

Dependencies and merge order

This draft depends on munich-quantum-toolkit/core#2273,
munich-quantum-toolkit/ddsim#978, and the publication of MQT DDSIM 2.6.0. Once
that release is available, regenerate and commit uv.lock, run the full
lint/test checks, and mark this pull request ready for review.

Validation

• source formatting, Ruff, and Markdown checks pass
• the uv-lock and ty checks cannot resolve the unreleased DDSIM 2.6.0
  dependency yet

AI assistance

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request description. A human must review and understand the changes before
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Checklist

• The pull request only contains commits that are focused and relevant to this change.
• Existing CSP and TSP tests cover the migrated sampling paths.
• No documentation update is required because the ProblemSolver API and behavior are unchanged.
• The changes follow the project's style guidelines and introduce no new warnings. Source checks pass; dependency-resolution checks await DDSIM 2.6.0.
• The changes are fully tested and pass the CI checks.
• I have reviewed my own code changes.

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[burgholzer]

The 3.10 fallback can be dropped as we are dropping 3.10 support everywhere (including here).