fix regression and improve curentChapter handling

with #745 I left som testing changes in the PR that resulted in currentChapter index not being updated. This is fixed now.

Also, the ScrollViewReader waiter 0.5s before jumping to the current Chapter. So it is always drawn correctly.

Signed-off-by: Toni Förster <toni.foerster@gmail.com>

Model/Player/Backends/MPVBackend.swift

@@ -464,6 +464,8 @@ final class MPVBackend: PlayerBackend {
         timeObserverThrottle.execute {
             self.model.updateWatch(time: self.currentTime)
         }
+
+        self.model.updateTime(self.currentTime!)
     }
 
     private func stopClientUpdates() {