style: replace external link icon with bookmark icon

Co-authored-by: aider (anthropic/claude-sonnet-4-20250514) <[e-mail]>

src/webapp/app/bookmarklet/page.tsx

···
   // Create the bookmarklet link using dangerouslySetInnerHTML to bypass React's security check
   const createBookmarkletLink = () => {
     return {
-      __html: `<a href="${bookmarkletCode}" style="text-decoration: none; padding: 8px 16px; background-color: var(--mantine-color-blue-6); color: white; border-radius: 4px; display: inline-flex; align-items: center; gap: 8px;"><svg width="16" height="16" viewBox="0 0 24 24" fill="currentColor"><path d="M14 3v2h3.59l-9.83 9.83 1.41 1.41L19 6.41V10h2V3h-7zM19 19H5V5h7V3H5c-1.1 0-2 .9-2 2v14c0 1.1.9 2 2 2h14c1.1 0 2-.9 2-2v-7h-2v7z"/></svg>Open in Semble</a>`
+      __html: `<a href="${bookmarkletCode}" style="text-decoration: none; padding: 8px 16px; background-color: var(--mantine-color-blue-6); color: white; border-radius: 4px; display: inline-flex; align-items: center; gap: 8px;"><svg width="16" height="16" viewBox="0 0 24 24" fill="currentColor"><path d="M17 3H7c-1.1 0-1.99.9-1.99 2L5 21l7-3 7 3V5c0-1.1-.9-2-2-2z"/></svg>Open in Semble</a>`
     };
   };