fix(historian-gateway): historize under the historian name, not the mux ref, when HistorianTagname overrides (FU-3)

The continuous-historization recorder conflated two identifiers into one string:
the dependency mux fans DependencyValueChanged keyed by the driver FullName
(the mux ref), but a value must be historized under the resolved historian name
(HistorianTagname override, else FullName). In the common no-override case the
two are equal, so it worked; with an override they diverge and the recorder
registered mux interest under a key the mux never fans — that tag's values were
never captured (and, had they been, would have been written under the mux ref).

Carry BOTH identifiers through the seam: a new HistorizedTagRef(MuxRef,
HistorianName) record on IHistorizedTagSubscriptionSink. The applier resolves
MuxRef = FullName and HistorianName = override-or-FullName. The recorder now
keeps a muxRef->historianName map: it registers/filters mux interest by MuxRef
but writes the outbox entry (and drains) under HistorianName. The convergence
handler re-registers the mux only when the registered key-set changes, so an
override-only rename (same FullName) updates the write target without mux churn.

Tests: a divergent-override recorder test (interest by mux ref, value written
under the override name, never the mux ref) + an override-rename no-churn test;
the applier feed tests now assert the full (mux ref, historian name) pairs.
Runtime 348/0, OpcUaServer 327/0; 0 warnings. Closes FU-3.

Claude-Session: https://claude.ai/code/session_012SDSQ3AcaXqPcBtDESBRii

src/Core/ZB.MOM.WW.OtOpcUa.Core.Abstractions/Historian/IHistorizedTagSubscriptionSink.cs

@@ -1,5 +1,35 @@
 namespace ZB.MOM.WW.OtOpcUa.Core.Abstractions;
 
+/// <summary>
+///     A single historized tag the recorder tracks, carrying BOTH identifiers it needs — kept distinct
+///     because a <c>HistorianTagname</c> override makes them diverge:
+///     <list type="bullet">
+///       <item>
+///         <see cref="MuxRef"/> — the driver-published reference the per-node dependency mux fans its
+///         <c>DependencyValueChanged</c> by (the tag's driver-side <c>FullName</c>). The recorder
+///         registers mux interest and matches incoming values by THIS.
+///       </item>
+///       <item>
+///         <see cref="HistorianName"/> — the resolved historian tag name the value is written under (a
+///         non-alarm historized value variable's <c>HistorianTagname</c> override, else its
+///         <c>FullName</c>) — the SAME name the EnsureTags provisioning hook ensures.
+///       </item>
+///     </list>
+///     In the common (no-override) case the two are the same string; an override is the only case they
+///     diverge, and conflating them would silently drop that tag's values (interest registered under a
+///     key the mux never fans).
+/// </summary>
+/// <param name="MuxRef">The driver ref the mux fans by (and the key the recorder registers interest under).</param>
+/// <param name="HistorianName">The resolved historian tag name the value is historized under.</param>
+public sealed record HistorizedTagRef(string MuxRef, string HistorianName)
+{
+    /// <summary>The no-override identity: the mux ref and historian name are the same string (the tag has
+    /// no <c>HistorianTagname</c> override, so it historizes under its own driver <c>FullName</c>).</summary>
+    /// <param name="reference">The driver ref that serves as both the mux key and the historian name.</param>
+    /// <returns>A ref whose <see cref="MuxRef"/> and <see cref="HistorianName"/> are equal.</returns>
+    public static HistorizedTagRef ForSelf(string reference) => new(reference, reference);
+}
+
 /// <summary>
 ///     Server-side feed that keeps the continuous-historization recorder's set of historized tag refs
 ///     in step with the deployed address space. The <c>AddressSpaceApplier</c> (in the
@@ -18,15 +48,16 @@ namespace ZB.MOM.WW.OtOpcUa.Core.Abstractions;
 public interface IHistorizedTagSubscriptionSink
 {
     /// <summary>
-    ///     Converge the recorder's historized-ref interest by an add/remove delta. The refs are
-    ///     resolved EXACTLY as the EnsureTags provisioning hook resolves them (a non-alarm historized
-    ///     value variable's <c>HistorianTagname</c> override, else its driver-side <c>FullName</c>).
-    ///     The recorder applies the delta to its tracked full set and re-registers mux interest only
-    ///     when the set actually changes.
+    ///     Converge the recorder's historized-ref interest by an add/remove delta. Each ref carries both
+    ///     its <see cref="HistorizedTagRef.MuxRef"/> (the driver ref the mux fans by) and its
+    ///     <see cref="HistorizedTagRef.HistorianName"/> (the resolved override-or-FullName the value is
+    ///     historized under) — the same name the EnsureTags provisioning hook ensures. The recorder
+    ///     applies the delta to its tracked full set and re-registers mux interest (keyed by
+    ///     <see cref="HistorizedTagRef.MuxRef"/>) only when the registered key-set actually changes.
     /// </summary>
     /// <param name="added">Historized refs newly historized by this deploy (added/changed-into tags).</param>
     /// <param name="removed">Historized refs no longer historized by this deploy (removed/changed-out tags).</param>
-    void UpdateHistorizedRefs(IReadOnlyList<string> added, IReadOnlyList<string> removed);
+    void UpdateHistorizedRefs(IReadOnlyList<HistorizedTagRef> added, IReadOnlyList<HistorizedTagRef> removed);
 }
 
 /// <summary>
@@ -42,7 +73,7 @@ public sealed class NullHistorizedTagSubscriptionSink : IHistorizedTagSubscripti
     private NullHistorizedTagSubscriptionSink() { }
 
     /// <inheritdoc />
-    public void UpdateHistorizedRefs(IReadOnlyList<string> added, IReadOnlyList<string> removed)
+    public void UpdateHistorizedRefs(IReadOnlyList<HistorizedTagRef> added, IReadOnlyList<HistorizedTagRef> removed)
     {
     }
 }