Replace native menu with custom titlebar

src/App.tsx

@@ -4,6 +4,8 @@ import {
   FileDown,
   FileInput,
   Languages,
+  Maximize2,
+  Minus,
   Plus,
   RefreshCcw,
   Settings,
@@ -328,6 +330,24 @@ export default function App() {
 
   return (
     <main className="appShell">
+      <section className="titlebar">
+        <div className="titlebarBrand">
+          <div className="titlebarMark">EH</div>
+          <span>EnvHelper</span>
+        </div>
+        <div className="windowControls">
+          <button onClick={() => window.envHelper?.minimizeWindow()} title="Minimize" type="button">
+            <Minus size={15} />
+          </button>
+          <button onClick={() => window.envHelper?.toggleMaximizeWindow()} title="Maximize" type="button">
+            <Maximize2 size={14} />
+          </button>
+          <button className="closeButton" onClick={() => window.envHelper?.closeWindow()} title="Close" type="button">
+            <X size={15} />
+          </button>
+        </div>
+      </section>
+
       <header className="toolbar">
         <div className="brand">
           <div className="brandMark">EH</div>