Revert "fix: make draw.io built-in save button work (#293)" (#294)

This reverts commit bcc6684ecb.

app/page.tsx

@@ -1,5 +1,5 @@
 "use client"
-import { useCallback, useEffect, useRef, useState } from "react"
+import { useEffect, useRef, useState } from "react"
 import { DrawIoEmbed } from "react-drawio"
 import type { ImperativePanelHandle } from "react-resizable-panels"
 import ChatPanel from "@/components/chat-panel"
@@ -21,8 +21,6 @@ export default function Home() {
         onDrawioLoad,
         resetDrawioReady,
         saveDiagramToStorage,
-        showSaveDialog,
-        setShowSaveDialog,
     } = useDiagram()
     const [isMobile, setIsMobile] = useState(false)
     const [isChatVisible, setIsChatVisible] = useState(true)
@@ -32,24 +30,6 @@ export default function Home() {
     const [closeProtection, setCloseProtection] = useState(false)
 
     const chatPanelRef = useRef<ImperativePanelHandle>(null)
-    const isSavingRef = useRef(false)
-
-    // Reset saving flag when dialog closes (with delay to ignore lingering save events from draw.io)
-    useEffect(() => {
-        if (!showSaveDialog && isSavingRef.current) {
-            const timeout = setTimeout(() => {
-                isSavingRef.current = false
-            }, 1000)
-            return () => clearTimeout(timeout)
-        }
-    }, [showSaveDialog])
-
-    // Handle save from draw.io's built-in save button
-    const handleDrawioSave = useCallback(() => {
-        if (isSavingRef.current) return
-        isSavingRef.current = true
-        setShowSaveDialog(true)
-    }, [setShowSaveDialog])
 
     // Load preferences from localStorage after mount
     useEffect(() => {
@@ -175,7 +155,6 @@ export default function Home() {
                                     ref={drawioRef}
                                     onExport={handleDiagramExport}
                                     onLoad={onDrawioLoad}
-                                    onSave={handleDrawioSave}
                                     baseUrl={drawioBaseUrl}
                                     urlParameters={{
                                         ui: drawioUi,