A run submitted without explicit inputs recorded `params = {}`: Port
initials filled the values at node level and were never written back, so an
exported row had a blank `param.*` cell and the runs listing could not tell
a run that took every default from one submitted with those same numbers.
Declared initials are now folded in at submit, explicit values winning, and
the run-level seed still wins over a declared one.
`params_digest` is computed over the resolved values, so it changes shape
once: a run recorded before this does not dedupe against a newer identical
submit, and its stage-cache entries miss once.
stroblme
c3ffa82792