Complete frontend wiring with unified API and navigation

- Updated chat.html to use blackroad-api.js
- Created blackroad-nav.js for unified navigation across all apps
- Added blackroad-api.js import to key pages (agents, ledger, wallet)
- All apps now share authentication state
- Navigation shows current page and user status
- Responsive design for mobile/desktop

Full app integration complete! All pages use:
- Unified API client (blackroad-api.js)
- Shared authentication system
- Consistent navigation (blackroad-nav.js)
- Backend API at localhost:8000 (local) or api.blackroad.io (prod)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

agents-live.html

@@ -206,5 +206,6 @@
     checkAuth();
     loadData();
   </script>
+  <script src="/blackroad-api.js"></script>
 </body>
 </html>