Remove noisy graph-snapshot logs and add waveform-sync diagnostics

- Strip the dense RenderWorkerPool debug messages about cached/stale graph
  snapshots and cleanup to reduce log spam.
- Add qDebug logging and status-bar feedback to
  TimelineWidget::SynchronizeSelectedClipsByWaveform() so we can see why the
  sync action does nothing (e.g. not enough cached clips or no usable offset).

app/render/renderworkerpool.cpp

@@ -579,14 +579,8 @@ bool RenderWorkerPool::PrepareJob(RenderTicketPtr ticket,
 		if (it != graph_cache_.end() && !project->is_modified()) {
 			graph_path = it->path;
 			AddGraphPathRefLocked(graph_path);
-			qDebug()
-				<< "RenderWorkerPool::PrepareJob: using cached graph snapshot"
-				<< graph_path;
 		} else {
 			if (it != graph_cache_.end()) {
-				qDebug()
-					<< "RenderWorkerPool::PrepareJob: graph stale, rewriting"
-					<< project->is_modified();
 				SetGraphPathCachedLocked(it->path, false);
 				graph_cache_.erase(it);
 			}
@@ -648,9 +642,6 @@ bool RenderWorkerPool::WriteGraphSnapshot(Project *project, QString *path)
 		return false;
 	}
 
-	qDebug() << "RenderWorkerPool wrote graph snapshot" << file.fileName()
-			 << "size" << QFileInfo(file.fileName()).size();
-
 	*path = file.fileName();
 	return true;
 }
@@ -1242,7 +1233,6 @@ void RenderWorkerPool::FinishWithFrame(RenderTicketPtr ticket,
 void RenderWorkerPool::CleanupGraphFile(const QString &path)
 {
 	if (!path.isEmpty()) {
-		qDebug() << "RenderWorkerPool cleaning up graph file" << path;
 		QFile::remove(path);
 	}
 }