[TATP-233]

Summary

• Pin unisim-core==2.5.0 in the default and ROCm profiles, including Motrix and SuperDex extras.
• Bump unilab to 1.5.6 and regenerate both lockfiles.
• Add the 1.5.6 changelog entry.
• Initialize the UniSim 2.5.0 Motrix mode field in tests that construct backend fakes with __new__.

Upstream release: https://github.com/unilabsim/unisim/releases/tag/v2.5.0

Validation

• make test-all — Ruff, mypy, and pyright passed; 2909 passed, 62 skipped, 375 deselected; benchmark imports 35/35 module-mode and 36/36 script-mode.
• uv run --no-sync pytest tests/base/test_backend_pre_step_control.py tests/base/test_motrix_backend_options.py tests/training/test_training_helpers.py -q — 58 passed.
• uv run --no-sync pytest tests/scripts/test_rocm_dependency_profile.py tests/scripts/test_check_docs.py -q — 25 passed.
• uv lock --check and the equivalent ROCm temporary-project check — passed.
• uv build --out-dir dist and uvx --from twine twine check dist/* — sdist and wheel passed; wheel metadata contains the three UniSim 2.5.0 requirements.
• Isolated wheel installation smoke — unilab 1.5.6; installed runtime reports unisim-core 2.5.0.