Improve language toggle button design

- Add globe icon to language toggle
- Style with border, proper padding, and hover effects
- Match overall nav design language
- Use Inter font for Arabic mode to show 'EN' consistently

src/App.css

@@ -307,6 +307,40 @@ html[dir="rtl"] {
   opacity: 1;
 }
 
+/* Language Toggle Button */
+.nav-lang-toggle {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  gap: 6px;
+  padding: 8px 14px;
+  border-radius: 8px;
+  font-size: 0.75rem;
+  font-weight: 600;
+  cursor: pointer;
+  transition: all 0.2s ease;
+  background: transparent;
+  border: 1px solid var(--border);
+  color: var(--text-muted);
+  min-width: 44px;
+  letter-spacing: 0.02em;
+}
+
+.nav-lang-toggle:hover {
+  background: var(--surface);
+  color: var(--text-primary);
+  border-color: var(--primary);
+}
+
+.nav-lang-toggle:active {
+  transform: scale(0.96);
+}
+
+/* RTL adjustments */
+html[dir="rtl"] .nav-lang-toggle {
+  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
+}
+
 /* Main Content */
 .dashboard,
 .comparison {