docs(deployment): defer embedded-ui guide to the companion UI PR

embedded-ui.md describes the production deployment story for the Reflex
embedded UI mode — that scope ships with the UI PR, not this
backend-hardening one.  Drop the file and the cross-link that points
to it from the environment-variables doc.

The content has been stashed locally and will return alongside the
rxconfig + reflex integration changes in the UI PR.

Author: fgogolli

docs/root/configuration/environment-variables.md

@@ -138,9 +138,6 @@ ORB_SCHEDULER_OVERRIDE=hostfactory
 `ORB_WORK_DIR` and `ORB_LOG_DIR` are documented under
 [Directory variables](#directory-variables) above.
 
-For the corresponding production deployment steps, see
-[Embedded UI deployment](../deployment/embedded-ui.md).
-
 ## HostFactory integration variables
 
 When running under IBM Spectrum LSF HostFactory, these variables are set by the scheduler and read by ORB's HostFactory adapter. They are not processed by the core config loader.