Scheduler allows one response per source per cycle by priority

Each source has a single response lane, so the scheduler picks one opcode with an if/else-if chain: retry re-ack, STOP for new request, STOP mid-wait, THROTTLE, MAX_BW, then RESUME. The first true condition wins and the rest are dropped that cycle. A granted request to a capped destination therefore gets MAX_BW and its RESUME is suppressed in that same cycle.