fix(opcuaserver): UNS reference nodes repair on backing-tag historian/shape edits

Adversarial review of 9f68f272 (classifier: non-alarm raw-tag deltas became
surgical) found stale UNS inheritance after a surgical raw edit. Editing a raw
tag's IsHistorized / HistorianTagname / IsArray / ArrayLength left every
referencing UNS node STALE: none of those fields were on UnsReferenceVariable,
so no coincident UnsReferenceDelta fired; the applier updated the raw node in
place; and EnsureVariable early-returns on an existing node. Consequences:
HistoryRead through the UNS NodeId served a different series than through the
raw NodeId (breaking the documented dual-registration invariant), a
de-historized tag kept serving history via UNS, and a scalar->array flip left
the UNS mirror scalar AND writable (bypassing the array read-only write gate).

UnsReferenceVariable now carries Backing{IsHistorized,HistorianTagname,IsArray,
ArrayLength}, copied from the backing tag's TagConfigIntent at compose time, so
record equality makes the reference Changed in the SAME plan. Both deltas are
non-rebuild kinds, so the existing machinery repairs the mirror surgically:
remove-previous in Apply, recreate in MaterialiseUnsReferences. That pass now
reads the four values from the RECORD (the single truth the planner diffed)
instead of a rawByPath back-lookup, preserving historian resolution exactly
(blank override => BackingRawPath, which is the backing tag's NodeId).

The artifact-decode seam needs no change: DeploymentArtifact.BuildRawAndUnsSubtrees
drives AddressSpaceComposer.Compose verbatim, which is what guarantees byte-parity.
The classifier needs no change either (a UnsReferenceDelta never forces Rebuild);
its comment now records why.

Also from the same review: a three-place-contract comment on RawTagPlan's
hand-written Equals naming its two downstream consumers, plus classifier pins for
the .Any(!eligible) quantifier, an ArrayLength-only delta, and an
alarm-content-only delta.

src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/AddressSpaceChangeClassifier.cs

@@ -74,6 +74,19 @@ public static class AddressSpaceChangeClassifier
         //   • ChangedUnsReferenceVariables ⇒ surgical remove-previous + recreate-current, applier-owned (a UNS
         //     reference variable is a mirror node binding no driver, so it carries no notifier wiring of its
         //     own — the alarm fan-out it participates in is re-derived from the raw tag's referencing set).
+        //     No rebuild is forced for a UNS-reference delta in EITHER direction, and that is load-bearing for
+        //     the repair path below.
+        // UNS-REFERENCE STALENESS, and why nothing here gates it (2026-08-15 review). Making non-alarm raw-tag
+        // deltas surgical meant a raw-side IsHistorized / HistorianTagname / IsArray / ArrayLength edit updated
+        // the raw node in place while every referencing UNS MIRROR node kept the old historian tagname + shape
+        // (EnsureVariable early-returns on an existing node) — wrong history series through the UNS NodeId, and
+        // a scalar→array flip left the mirror scalar AND writable. The fix is in the RECORD, not the classifier:
+        // UnsReferenceVariable now carries the backing tag's Backing{IsHistorized,HistorianTagname,IsArray,
+        // ArrayLength}, so the same edit makes the reference record unequal and the planner emits a COINCIDENT
+        // UnsReferenceDelta alongside the RawTagDelta. Both are non-rebuild kinds, so the plan stays
+        // AttributeOnly and the applier repairs the mirror surgically (remove-previous + materialise-recreate).
+        // Adding a new inherited field to UnsReferenceVariable therefore needs no change here — but OMITTING one
+        // silently reopens the staleness.
         // Anything a future surgical raw-tag path lets through that DOES touch alarm notifiers must still
         // re-wire/unwire them (WireAlarmNotifiers is a reconcile — pass the tag's COMPLETE current referencing
         // set — plus an explicit unwire on removal), else a de-referenced equipment keeps receiving the events.