Test ML Pipeline (router)

Where tests for an ML workspace live, what gets paired with what, and which subskill owns the body of each test category.

First action (every turn)

Before answering anything else:

1. Confirm an approved design note exists for the test the user is asking about. The pairing rule is hard: tests/<category>/test_NN_<short_name>.py only exists if journal/NN_<short_name>.md is at least approved and experiments/NN_<short_name>.py is the matching script. If the design note doesn't exist, hand back to iterate-ml-experiment.
2. Emit the Pre-flight checklist (below) as visible text in your response, with each box marked.
3. Use the Dispatch table to pick the subskill that owns the test category, then hand off.