Fix React 18 type incompatibility with react-split-pane using type cast

Co-authored-by: thomasnordquist <7721625+thomasnordquist@users.noreply.github.com>

Author: Copilot

app/src/components/Layout/ContentView.tsx

@@ -1,6 +1,6 @@
 import * as React from 'react'
 import ChartPanel from '../ChartPanel'
-import ReactSplitPane from 'react-split-pane'
+import ReactSplitPaneImport from 'react-split-pane'
 import Tree from '../Tree'
 import { AppState } from '../../reducers'
 import { ChartParameters } from '../../reducers/Charts'
@@ -9,6 +9,9 @@ import { List } from 'immutable'
 import { Sidebar } from '../Sidebar'
 import { useResizeDetector } from 'react-resize-detector'
 
+// Type cast to any to work around React 18 compatibility issues with react-split-pane 0.1.x
+const ReactSplitPane = ReactSplitPaneImport as any
+
 interface Props {
   heightProperty: any
   paneDefaults: any