pack: add .editorconfig and use tab instead of space

src/renderer/index.html

@@ -1,10 +1,10 @@
 <!DOCTYPE html>
 <html>
-  <head>
-    <meta charset="utf-8" />
-  </head>
-  <body>
-    <div id="app"></div>
-  </body>
-  <script type="module" src="./main.ts"></script>
+	<head>
+		<meta charset="utf-8" />
+	</head>
+	<body>
+		<div id="app"></div>
+	</body>
+	<script type="module" src="./main.ts"></script>
 </html>