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.'

app/[lang]/page.tsx

@@ -11,16 +11,10 @@ import {
 } from "@/components/ui/resizable"
 import { useDiagram } from "@/contexts/diagram-context"
 import { i18n, type Locale } from "@/lib/i18n/config"
-import { isIndexedDBUsable } from "@/lib/session-storage"
 
 export default function Home() {
-    const {
-        drawioRef,
-        handleDiagramExport,
-        handleDiagramAutoSave,
-        onDrawioLoad,
-        resetDrawioReady,
-    } = useDiagram()
+    const { drawioRef, handleDiagramExport, onDrawioLoad, resetDrawioReady } =
+        useDiagram()
     const router = useRouter()
     const pathname = usePathname()
     // Extract current language from pathname (e.g., "/zh/about" → "zh")
@@ -32,7 +26,6 @@ export default function Home() {
     const [isLoaded, setIsLoaded] = useState(false)
     const [isDrawioReady, setIsDrawioReady] = useState(false)
     const [isElectron, setIsElectron] = useState(false)
-    const [canPersist, setCanPersist] = useState(false)
     const [drawioBaseUrl, setDrawioBaseUrl] = useState(
         process.env.NEXT_PUBLIC_DRAWIO_BASE_URL || "https://embed.diagrams.net",
     )
@@ -83,10 +76,6 @@ export default function Home() {
             setDrawioBaseUrl(`${window.location.origin}/drawio/index.html`)
         }
 
-        void (async () => {
-            const usable = await isIndexedDBUsable()
-            setCanPersist(usable)
-        })()
         setIsLoaded(true)
     }, [pathname, router])
 
@@ -95,17 +84,6 @@ export default function Home() {
         onDrawioLoad()
     }, [onDrawioLoad])
 
-    const handleDrawioAutoSave = useCallback(
-        (data: { xml?: string }) => {
-            handleDiagramAutoSave(data)
-            // Only suppress modified state when persistence is available
-            if (canPersist) {
-                drawioRef.current?.status({ message: "", modified: false })
-            }
-        },
-        [canPersist, drawioRef, handleDiagramAutoSave],
-    )
-
     const handleDarkModeChange = () => {
         const newValue = !darkMode
         setDarkMode(newValue)
@@ -196,25 +174,13 @@ export default function Home() {
                                     <DrawIoEmbed
                                         key={`${drawioUi}-${darkMode}-${currentLang}-${isElectron}`}
                                         ref={drawioRef}
-                                        autosave
-                                        onAutoSave={handleDrawioAutoSave}
                                         onExport={handleDiagramExport}
                                         onLoad={handleDrawioLoad}
                                         baseUrl={drawioBaseUrl}
-                                        configuration={
-                                            canPersist
-                                                ? { confirmExit: false }
-                                                : undefined
-                                        }
                                         urlParameters={{
                                             ui: drawioUi,
                                             spin: false,
                                             libraries: false,
-                                            // Disable modified tracking only when persistence is available
-                                            ...(canPersist && {
-                                                modified: false,
-                                                keepmodified: false,
-                                            }),
                                             saveAndExit: false,
                                             noSaveBtn: true,
                                             noExitBtn: true,