fix: address accessibility and breakpoint issues in mobile menu

- Fix overlay to use role=presentation instead of role=button
- Add rel=noopener noreferrer to external links in mobile menu
- Show mobile menu at 1024px to match when desktop nav hides

Author: chris-stinemetz

src/app.scss

@@ -731,8 +731,8 @@ body::before {
   .contact-container { padding: 60px 24px; }
 }
 
-/* Mobile specific */
-@media (max-width: 768px) {
+/* Tablet - show mobile menu button when nav is hidden */
+@media (max-width: 1024px) {
   .mobile-menu-btn {
     display: flex;
   }
@@ -799,7 +799,10 @@ body::before {
     width: 100%;
     justify-content: center;
   }
-  
+}
+
+/* Mobile specific - smaller screens */
+@media (max-width: 768px) {
   /* Hero adjustments */
   .hero {
     padding: 40px 16px;

src/routes/+layout.svelte

@@ -104,18 +104,21 @@
 
 <!-- Mobile Menu Overlay -->
 {#if mobileMenuOpen}
+	<!-- svelte-ignore a11y_no_noninteractive_tabindex -->
 	<div
 		class="mobile-menu-overlay"
 		onclick={closeMobileMenu}
-		role="button"
-		tabindex="-1"
-		aria-label="Close menu"
+		onkeydown={(e) => e.key === 'Escape' && closeMobileMenu()}
+		tabindex="0"
+		role="presentation"
+		aria-hidden="true"
 	></div>
 	<nav class="mobile-menu">
 		<a
 			href="https://www.npmjs.com/package/@context-engine-bridge/context-engine-mcp-bridge"
 			class="mobile-nav-link"
 			target="_blank"
+			rel="noopener noreferrer"
 			onclick={closeMobileMenu}
 		>
 			<svg viewBox="0 0 24 24" fill="currentColor" width="20" height="20">
@@ -129,6 +132,7 @@
 			href="https://github.com/Context-Engine-AI/Context-Engine"
 			class="mobile-nav-link"
 			target="_blank"
+			rel="noopener noreferrer"
 			onclick={closeMobileMenu}
 		>
 			<Github size={20} />
@@ -138,6 +142,7 @@
 			href="https://marketplace.visualstudio.com/items?itemName=context-engine.context-engine-uploader"
 			class="mobile-nav-link"
 			target="_blank"
+			rel="noopener noreferrer"
 			onclick={closeMobileMenu}
 		>
 			<svg viewBox="0 0 24 24" fill="currentColor" width="20" height="20">