Specs expansion to cover highly structured populations #10
Description
Files: specs.py, __init__.py, test_op_system_specs.py.
add axes/state_axes parsing, broadcast/expand axes, broadcast, repeat_over, axis groups/slices), vector/scalar param broadcast, proportional target filters; emit meta with axes/mixing/operators plus optional debug-expansion. Preserve NormalizedRhs name for now but, add new fields.