Keep what each machine says of what it runs, raise it, and gate on it (hq ADR 0240, to-be 48 Phase A)

The gate judged a module by what the mesh saw from outside, so a container that
crash-looped after it applied passed it. Each machine's node-engine now states
the health of every long-running resource it runs; the controller keeps the
newest statement per machine, raises module.<module>.<machine>.unhealthy on the
second statement in a row, clears it on the first that does not say it, and the
gate passes a module only when every long-running resource of it is stated
healthy since the send. An engine that states nothing is judged as before.

internal/link/receive.go

@@ -30,8 +30,10 @@ const (
 	KindHeartbeat = "heartbeat"
 	// KindToolsHeartbeat is a machine's node tools saying they are there (novox/hq to-be 45 S11).
 	KindToolsHeartbeat = "tools-heartbeat"
-	KindBuilt          = "built"
-	KindModuleMoved    = "module-moved"
+	// KindHealth is a machine's statement of its long-running resources' health (novox/hq ADR 0240).
+	KindHealth      = "health"
+	KindBuilt       = "built"
+	KindModuleMoved = "module-moved"
 	// KindSourceMoved is the forge announcing a merge: a source moved, and what it produces is
 	// built without anybody telling the mesh (novox/hq 04-ISSUES/131).
 	KindSourceMoved = "source-moved"