fix: Update imports to use engine.pipeline instead of engine.pipeline.core

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.

engine/pipeline/__init__.py

@@ -26,6 +26,11 @@ from sideline.pipeline import (
     register_source,
 )
 
+# Also re-export from sideline.core for compatibility
+from sideline.pipeline.core import (
+    DataType,
+)
+
 # Re-export from engine.pipeline.presets (Mainline-specific)
 from engine.pipeline.presets import (
     DEMO_PRESET,
@@ -91,4 +96,6 @@ __all__ = [
     "register_effect",
     "register_display",
     "register_camera",
+    # Core types (from sideline)
+    "DataType",
 ]