fix runner expire during active use. Clearing the expire timer as it is used....

fix runner expire during active use.  Clearing the expire timer as it is used.  Allowing the finish to assign an expire timer so that the runner will expire after no use.

server/sched.go

@@ -296,6 +296,10 @@ func (pending *LlmRequest) useLoadedRunner(runner *runnerRef, finished chan *Llm
 	runner.refMu.Lock()
 	defer runner.refMu.Unlock()
 	runner.refCount++
+	if runner.expireTimer != nil {
+		runner.expireTimer.Stop()
+		runner.expireTimer = nil
+	}
 	runner.sessionDuration = pending.sessionDuration
 	pending.successCh <- runner
 	go func() {