Implement normalized loader capabilities model

[AssociatedPrimeIdeal]

Closes #9

Summary

• add typed normalized loader result and loader capability flags
• make segmentation and TKE optional through load/pipeline/workspace state
• compute WSS/TKE lazily, and skip TKE when the input has no complex source
• add focused tests for legacy and normalized loader capability behavior

Verification

• ~/miniconda3/envs/ryy/bin/python -m pytest -q tests/test_loader_capabilities.py tests/test_config_workspace.py tests/test_imports.py