Zeroed status bit can go undetected when no consumer reads it

Injecting status_out[p][ST_BACKPRESSURE] = 0 produced no test failure because the bit was a dead write: the integration only extracts the occupancy field [ST_COUNT_LSB +: OCC_W] from status_out and feeds it to the scheduler. Before assuming a test covers a status bit, grep for every consumer of that bit. Coverage gaps need a direct assertion on the bit value (high when queue >= BP_LEVEL, low after drain).