Separate processing, rendering, and reporting utilities

[AssociatedPrimeIdeal]

Closes #6

Summary:

• split processing, plane I/O, reporting, and rendering helpers out of autoflow/utils.py
• reorganize core state/pipeline and UI modules into autoflow/core and autoflow/ui
• keep legacy module paths as compatibility shims and extend import coverage tests

Testing:

• /home/renyuyang/miniconda3/envs/ryy/bin/python -m pytest -q tests/test_imports.py tests/test_config_workspace.py tests/test_demo_workflows.py tests/test_smoke_phantoms.py