The old engine/pipeline/core.py file was removed as part of the Sideline/Mainline split.
All imports that referenced engine.pipeline.core have been updated to use engine.pipeline
which re-exports from sideline.pipeline.core.
This ensures consistency and avoids duplicate DataType enum instances.
- Move effects_plugins/ to engine/effects/plugins/
- Update imports in engine/app.py
- Update imports in all test files
- Follows capability-based deps architecture
Closes#27
