Open OpenHands UI to all interfaces

Was bound to 127.0.0.1:3030 — overcautious on a Tailscale-only box
where Phoenix/Beszel/OpenWebUI are all reached the same way. Updated
the homepage tile description and added a security note in the README
for the case where the host ever leaves the tailnet.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

pyinfra/framework/compose/homepage/services.yaml

@@ -47,7 +47,7 @@
     - OpenHands:
         icon: mdi-robot
         href: http://framework:3030
-        description: Autonomous coding agent (loopback — needs SSH tunnel)
+        description: Autonomous coding agent in a Docker sandbox
         server: localhost-docker
         container: openhands