fix(trajectory): stabilize timeline pane layering

packages/client/ui-trajectory/src/client/TrajectoryTable.module.css

@@ -828,6 +828,7 @@
   flex: 1;
   min-height: 0;
   overflow: auto;
+  scrollbar-gutter: stable;
 }
 
 .detailBodySummary {

packages/client/ui-trajectory/src/client/TrajectoryTimeline.module.css

@@ -1,6 +1,6 @@
 .root {
   position: relative;
-  z-index: 0;
+  z-index: 1;
   isolation: isolate;
   flex: none;
   border-bottom: 1px solid var(--dsw-alias-border-l2);

packages/client/ui-trajectory/src/client/views.module.css

@@ -27,6 +27,9 @@
 }
 
 .ledger {
+  position: relative;
+  z-index: 0;
+  isolation: isolate;
   display: flex;
   flex: 1;
   min-height: 0;