Add fourth test question to ACT-1 outcomes

Added test: 'Explain the difference between a UID and a port.'

This verifies readers understand UIDs and ports are different things
that share the SMEP numbering scheme.

docs/ooda/2025-10-multi-service-architecture/outcomes.md

···
 - "What is the difference between `machine` and `service` in the context of tinsnip?"
 - "How is a uid constructed?"
 - "What do each of the uid digits identify using tinsnip terminology?"
+- "Explain the difference between a UID and a port."
 
 ## machine-metadata