[WEB-5585]chore: timeline chart refactor (#8246)

* chore: timeline chart refactor

* fix: format

apps/web/ce/components/gantt-chart/index.ts

@@ -1 +1,2 @@
 export * from "./dependency";
+export * from "./layers";

apps/web/ce/components/gantt-chart/layers/additional-layers.tsx

@@ -0,0 +1,8 @@
+import type { FC } from "react";
+
+type Props = {
+  itemsContainerWidth: number;
+  blockCount: number;
+};
+
+export const GanttAdditionalLayers: FC<Props> = () => null;

apps/web/ce/components/gantt-chart/layers/index.ts

@@ -0,0 +1 @@
+export { GanttAdditionalLayers } from "./additional-layers";

apps/web/core/components/gantt-chart/chart/main-content.tsx

@@ -17,7 +17,11 @@ import { GanttChartSidebar, MonthChartView, QuarterChartView, WeekChartView } fr
 // hooks
 import { useTimeLineChartStore } from "@/hooks/use-timeline-chart";
 // plane web components
-import { TimelineDependencyPaths, TimelineDraggablePath } from "@/plane-web/components/gantt-chart";
+import {
+  TimelineDependencyPaths,
+  TimelineDraggablePath,
+  GanttAdditionalLayers,
+} from "@/plane-web/components/gantt-chart";
 import { GanttChartRowList } from "@/plane-web/components/gantt-chart/blocks/block-row-list";
 import { GanttChartBlocksList } from "@/plane-web/components/gantt-chart/blocks/blocks-list";
 import { IssueBulkOperationsRoot } from "@/plane-web/components/issues/bulk-operations";
@@ -212,6 +216,7 @@ export const GanttChartMainContent = observer(function GanttChartMainContent(pro
                     />
                     <TimelineDependencyPaths isEpic={isEpic} />
                     <TimelineDraggablePath />
+                    <GanttAdditionalLayers itemsContainerWidth={itemsContainerWidth} blockCount={blockIds.length} />
                     <GanttChartBlocksList
                       blockIds={blockIds}
                       blockToRender={blockToRender}