Revert "fix(electron): prevent beforeunload prompt by using autosave (#642)" (#646)

This reverts commit e7c29fb410.

The PR introduced an IndexedDB error: 'Failed to execute transaction on IDBDatabase: The database connection is closing.'

contexts/diagram-context.tsx

@@ -20,10 +20,9 @@ interface DiagramContextType {
     loadDiagram: (chart: string, skipValidation?: boolean) => string | null
     handleExport: () => void
     handleExportWithoutHistory: () => void
-    resolverRef: React.MutableRefObject<((value: string) => void) | null>
-    drawioRef: React.MutableRefObject<DrawIoEmbedRef | null>
+    resolverRef: React.Ref<((value: string) => void) | null>
+    drawioRef: React.Ref<DrawIoEmbedRef | null>
     handleDiagramExport: (data: any) => void
-    handleDiagramAutoSave: (data: { xml?: string }) => void
     clearDiagram: () => void
     saveDiagramToFile: (
         filename: string,
@@ -268,11 +267,6 @@ export function DiagramProvider({ children }: { children: React.ReactNode }) {
         }
     }
 
-    const handleDiagramAutoSave = (data: { xml?: string }) => {
-        if (!data?.xml) return
-        setChartXML(data.xml)
-    }
-
     const clearDiagram = () => {
         const emptyDiagram = `<mxfile><diagram name="Page-1" id="page-1"><mxGraphModel><root><mxCell id="0"/><mxCell id="1" parent="0"/></root></mxGraphModel></diagram></mxfile>`
         // Skip validation for trusted internal template (loadDiagram also sets chartXML)
@@ -397,7 +391,6 @@ export function DiagramProvider({ children }: { children: React.ReactNode }) {
                 resolverRef,
                 drawioRef,
                 handleDiagramExport,
-                handleDiagramAutoSave,
                 clearDiagram,
                 saveDiagramToFile,
                 getThumbnailSvg,