Update README: Tailscale integration is now built

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

README.md

@@ -23,10 +23,15 @@ Built so far:
 - **Servers & Tasks** — cron/systemd tracking across Debian/Raspbian servers
   via a lightweight push agent (`agent/linux/`), plus manual entries for
   things an agent can't see (Docker jobs, backups)
+- **Integrations → Tailscale** — device list with online/authorized status,
+  and authorize/deauthorize/remove actions; a live device-count widget on
+  the Dashboard. First of the six planned live integrations; the same
+  config-in-UI + encrypted-credentials pattern as DNS providers, so the
+  remaining five slot into the same "Add integration" form as they're built.
 
 Not yet built (see `.claude/plans` for the full delivery plan):
 
-- Live integrations: Proxmox, Synology, Semaphore, Tailscale, Gitea, Dockhand
+- Remaining live integrations: Proxmox, Synology, Semaphore, Gitea, Dockhand
 
 ## Requirements