Change webpack configs to mjs

For some reason node insists on loading them as commonjs despite
"type": "module" in package.json. This leads to import errors
in node 23.

Issue #234

package.json

@@ -9,9 +9,9 @@
     "tauri-dev": "tauri dev",
     "build": "tauri build",
     "build-bin": "tauri build -b none",
-    "webpack-serve": "webpack serve --config webpack.dev.js",
-    "webpack-dev": "webpack --config webpack.dev.js",
-    "webpack-prod": "webpack --config webpack.prod.js",
+    "webpack-serve": "webpack serve --config webpack.dev.mjs",
+    "webpack-dev": "webpack --config webpack.dev.mjs",
+    "webpack-prod": "webpack --config webpack.prod.mjs",
     "info": "tauri info",
     "react-devtools": "npx react-devtools"
   },

webpack.dev.js → webpack.dev.mjs

@@ -17,7 +17,7 @@
  */
 
 import { merge } from "webpack-merge";
-import common from "./webpack.common.js";
+import common from "./webpack.common.mjs";
 
 export default merge(common("development"), {
     devtool: "source-map",

webpack.prod.js → webpack.prod.mjs

@@ -17,7 +17,7 @@
  */
 
 import { merge } from "webpack-merge";
-import common, { __dirname } from "./webpack.common.js";
+import common, { __dirname } from "./webpack.common.mjs";
 import path from "path";
 import { BundleAnalyzerPlugin } from "webpack-bundle-analyzer";