Count rows of a target entity right now.
the target entity (model's training-unit entity)
optional filter narrowing the population (mirrors the pipeline scope)
request user — required server-side for isolation/audit
the provider the count goes through (required: no fallback to the global provider)
RunView-backed IRowCounter. Uses thecount_onlyresult type so the full population size lands inTotalRowCountWITHOUT materializing any rows — the efficient way to get a current count for the data-volume / drift triggers.