feat: highlight 'your own highlights' in login copy

- Style 'your own highlights' text with user's mine highlight color
- Uses --highlight-color-mine CSS variable from settings
- Adds subtle padding and border-radius for clean highlight effect

src/components/LoginOptions.tsx

@@ -78,7 +78,7 @@ const LoginOptions: React.FC = () => {
       <div className="login-content">
         <h2 className="login-title">Welcome to Boris</h2>
         <p className="login-description">
-          Login to see your bookmarks, explore long-form articles, and create your own highlights.
+          Login to see your bookmarks, explore long-form articles, and create <mark className="login-highlight">your own highlights</mark>.
         </p>
         
         <div className="login-buttons">

src/styles/components/login.css

@@ -27,6 +27,14 @@
   text-align: center;
 }
 
+.login-highlight {
+  background-color: var(--highlight-color-mine, #fde047);
+  color: var(--color-text);
+  padding: 0.125rem 0.25rem;
+  border-radius: 3px;
+  font-weight: 500;
+}
+
 .login-buttons {
   display: flex;
   flex-direction: column;