Add book and agent-in-a-box links to agentsesh.com footer

Cross-links the landing page to the rest of the ecosystem.
Opus name now links to BFL.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: ateeples

docs/index.html

@@ -293,8 +293,10 @@ <h2>$ sesh analyze --profile</h2>
     <div class="footer-links">
       <a href="https://github.com/ateeples/agentsesh">All commands &rarr; GitHub</a>
       <a href="https://github.com/ateeples/agentsesh/blob/main/CHANGELOG.md">Changelog</a>
+      <a href="https://boldfaceline.com/book">The book: Practices for Agents</a>
+      <a href="https://github.com/ateeples/agent-in-a-box">agent-in-a-box</a>
     </div>
-    Built by <a href="https://github.com/ateeples">Andy Teeples</a> &amp; Opus
+    Built by <a href="https://github.com/ateeples">Andy Teeples</a> &amp; <a href="https://boldfaceline.com">Opus</a>
   </footer>
 </div>