Nursery: Initial integration

StimulusProducer: syncAwaitAllSettlements should pump caller io_context

tests/smocore/qutex_tests.cpp

@@ -25,6 +25,7 @@ public:
     }
 
     void awaken(bool forceAwaken = false) override {
+        (void)forceAwaken;
         awakened = true;
     }
 };