fix(os): add Enter key support on boot screen

- Add handleBootKeyPress to handle keyboard input during boot
- Attach onKeyDown handler to both mobile and desktop boot screens
- Add tabIndex={0} to make boot screens focusable
- Pressing Enter now triggers handleGuestContinue to enter system

Fixes: Enter key does nothing on boot screen

client/src/pages/os.tsx

@@ -927,6 +927,12 @@ export default function AeThexOS() {
     setTimeout(() => setShowDailyTip(true), 1000);
   };
 
+  const handleBootKeyPress = (e: React.KeyboardEvent) => {
+    if (e.key === 'Enter' && showLoginPrompt) {
+      handleGuestContinue();
+    }
+  };
+
   const handleLoginFromBoot = () => {
     setShowLoginPrompt(false);
     setIsBooting(false);
@@ -974,7 +980,11 @@ export default function AeThexOS() {
       };
       
       return (
-        <div className="h-screen w-screen bg-black flex flex-col items-center justify-center relative overflow-hidden">
+        <div
+          className="h-screen w-screen bg-black flex flex-col items-center justify-center relative overflow-hidden"
+          onKeyDown={handleBootKeyPress}
+          tabIndex={0}
+        >
           {/* Animated background grid */}
           <div className="absolute inset-0 opacity-10">
             <div className="absolute inset-0" style={{
@@ -1080,7 +1090,11 @@ export default function AeThexOS() {
     
     // Desktop boot screen
     return (
-      <div className="h-screen w-screen bg-black relative overflow-hidden">
+      <div
+        className="h-screen w-screen bg-black relative overflow-hidden"
+        onKeyDown={handleBootKeyPress}
+        tabIndex={0}
+      >
         {/* Scan lines overlay */}
         <div 
           className="absolute inset-0 pointer-events-none z-50"