_run_materialized_pass distinguishes due-check skips from in-flight
skips and never calls state.set_error for either. summary['skipped']
becomes a list of {table, reason} dicts; the end-of-pass log line
breaks out the in_flight subcount.
Hoists is_table_due to module-level import so test monkeypatching of
the symbol intercepts the call (the previous local import made
patches a no-op).
