fix: log Editable SVG saves, use local dates in file names, drop unused Electron dialogs

- /api/log-save accepted only drawio, png and svg, so saving as Editable
  SVG (xmlsvg) got a 400 and was never recorded in Langfuse
- The default download name and the template export name used the UTC
  date, which is the previous day on mornings in East Asia
- Remove the Electron openFile/saveFile IPC handlers, their preload
  bindings and types; nothing in the app calls them

electron/electron.d.ts

@@ -60,10 +60,6 @@ declare global {
             maximize: () => void
             /** Close the window */
             close: () => void
-            /** Open file dialog and return file path */
-            openFile: () => Promise<string | null>
-            /** Save data to file via save dialog */
-            saveFile: (data: string) => Promise<boolean>
             /** Get proxy configuration */
             getProxy: () => Promise<ProxyConfig>
             /** Set proxy configuration (saves and restarts server) */

electron/main/ipc-handlers.ts

@@ -1,10 +1,4 @@
-import {
-    app,
-    BrowserWindow,
-    dialog,
-    type IpcMainInvokeEvent,
-    ipcMain,
-} from "electron"
+import { app, BrowserWindow, type IpcMainInvokeEvent, ipcMain } from "electron"
 import { rebuildAppMenu, switchPreset } from "./app-menu"
 import {
     type ConfigPreset,
@@ -104,60 +98,6 @@ export function registerIpcHandlers(): void {
         win?.close()
     })
 
-    // ==================== File Dialogs ====================
-
-    handle("dialog-open-file", async (event) => {
-        const win = BrowserWindow.fromWebContents(event.sender)
-        if (!win) return null
-
-        const result = await dialog.showOpenDialog(win, {
-            properties: ["openFile"],
-            filters: [
-                { name: "Draw.io Files", extensions: ["drawio", "xml"] },
-                { name: "All Files", extensions: ["*"] },
-            ],
-        })
-
-        if (result.canceled || result.filePaths.length === 0) {
-            return null
-        }
-
-        // Read the file content
-        const fs = await import("node:fs/promises")
-        try {
-            const content = await fs.readFile(result.filePaths[0], "utf-8")
-            return content
-        } catch (error) {
-            console.error("Failed to read file:", error)
-            return null
-        }
-    })
-
-    handle("dialog-save-file", async (event, data: string) => {
-        const win = BrowserWindow.fromWebContents(event.sender)
-        if (!win || typeof data !== "string") return false
-
-        const result = await dialog.showSaveDialog(win, {
-            filters: [
-                { name: "Draw.io Files", extensions: ["drawio"] },
-                { name: "XML Files", extensions: ["xml"] },
-            ],
-        })
-
-        if (result.canceled || !result.filePath) {
-            return false
-        }
-
-        const fs = await import("node:fs/promises")
-        try {
-            await fs.writeFile(result.filePath, data, "utf-8")
-            return true
-        } catch (error) {
-            console.error("Failed to save file:", error)
-            return false
-        }
-    })
-
     // ==================== Config Presets ====================
 
     handle("config-presets:get-all", () => {

electron/preload/index.ts

@@ -18,10 +18,6 @@ contextBridge.exposeInMainWorld("electronAPI", {
     maximize: () => ipcRenderer.send("window-maximize"),
     close: () => ipcRenderer.send("window-close"),
 
-    // File operations
-    openFile: () => ipcRenderer.invoke("dialog-open-file"),
-    saveFile: (data: string) => ipcRenderer.invoke("dialog-save-file", data),
-
     // Proxy settings
     getProxy: () => ipcRenderer.invoke("get-proxy"),
     setProxy: (config: { httpProxy?: string; httpsProxy?: string }) =>