fix: use ESM imports instead of require in Electron main

electron/main.mjs

@@ -1,7 +1,8 @@
 import { app, BrowserWindow, ipcMain, dialog } from 'electron';
 import path from 'path';
 import { fileURLToPath } from 'url';
-import { createServer } from 'http';
+import http from 'http';
+import fs from 'fs';
 
 const __filename = fileURLToPath(import.meta.url);
 const __dirname = path.dirname(__filename);
@@ -44,9 +45,8 @@ function getDistPath() {
 
 function loadDistServer() {
   const distPath = getDistPath();
-  const indexPath = path.join(distPath, 'index.html');
   
-  const server = require('http').createServer((req, res) => {
+  const server = http.createServer((req, res) => {
     let filePath = path.join(distPath, req.url === '/' ? 'index.html' : req.url);
     
     if (!filePath.startsWith(distPath)) {
@@ -67,7 +67,6 @@ function loadDistServer() {
       '.md': 'text/markdown',
     };
     
-    const fs = require('fs');
     if (fs.existsSync(filePath)) {
       const contentType = contentTypes[ext] || 'application/octet-stream';
       res.writeHead(200, { 'Content-Type': contentType });