[codex] fix bin entrypoint imports

[vvv214]

Fix public dpsynth/bin CLI entrypoints so they start from the open-source package.

Changes:

• fix the indentation error and missing internal imports in run_data_generation.py
• remove the missing fancyflags dependency from main.py and comparison.py
• lazily import sdmetrics when comparison report generation runs
• fix run_tabular_eval.py local CSV execution (csv flag value, enum values, dataclass output)
• add bin CLI smoke coverage for all public entrypoints and a local CSV eval run

Validation:

• PYTHONPATH=/tmp/dpsynth-test-stubs:. JAX_ENABLE_X64=True /tmp/dpsynth-py312/bin/python -m compileall -q dpsynth/bin tests/bin
• PYTHONPATH=/tmp/dpsynth-test-stubs:. JAX_ENABLE_X64=True /tmp/dpsynth-py312/bin/python -m pytest tests/bin -q
• git diff --check
• git diff origin/main...HEAD --check