fix: exempt enum null-clearing sentinel '' from parity tool (#401 follow-up) (#402)

PR #401 added '' to the ValidateSet of -Duplex, -POE_Mode, -POE_Type,
and -RF_Role on Set-NBDCIMInterface as an empty-string sentinel. The
sentinel is translated to \$null in process {} before JSON body
serialization, so NetBox sees {"field": null} and clears the value.

scripts/Verify-ValidateSetParity.ps1 has no way to know the '' is a
PowerNetbox-internal clearing marker rather than a real value, so it
flagged these as 'Extra in PowerNetbox'. That's expected, not a bug —
add four exemptions with an explanatory comment pointing at PR #401.

Also adds RF_Role preventively: it doesn't currently surface in the
parity output (score below match threshold) but uses the same
sentinel pattern, so if a future NetBox change shifts the score
above threshold the exemption is already in place.

Tool output: 8 -> 5 findings against both v4.5.8 and v4.6.0-beta1
(the 5 remaining are the pre-existing #392 catalog-adds plus the
known Get-NBBranch wrong-class match).

Author: ctrl-alt-automate

scripts/validateset-parity-exclusions.txt

@@ -44,3 +44,15 @@ Extras/CustomLinks/Set-NBCustomLink.ps1::Button_Class
 # '100', '200', '300', '400' — translate to: 'access', 'tagged', 'tagged-all', 'q-in-q'.
 DCIM/Interfaces/New-NBDCIMInterface.ps1::Mode
 DCIM/Interfaces/Set-NBDCIMInterface.ps1::Mode
+
+# ---------------------------------------------------------------------------
+# Parameters that include '' as an empty-string sentinel for null-clearing
+# on PATCH. Translated to $null in process {} before the JSON body is built
+# (see PR #401 — Set-NBDCIMInterface enum null-clearing follow-up to PR #398).
+# The '' is a PowerNetbox UX choice, not a value NetBox actually accepts —
+# so the parity tool flags it as "Extra in PowerNetbox". That's expected.
+# ---------------------------------------------------------------------------
+DCIM/Interfaces/Set-NBDCIMInterface.ps1::Duplex
+DCIM/Interfaces/Set-NBDCIMInterface.ps1::POE_Mode
+DCIM/Interfaces/Set-NBDCIMInterface.ps1::POE_Type
+DCIM/Interfaces/Set-NBDCIMInterface.ps1::RF_Role