feat(acl): keys + ACLs reach driver-only nodes via the artifact (#520 stage 4)

A driver-only node has had no ConfigDb since per-cluster mesh Phase 4, so it
registered NullOpcUaUserAuthenticator and denied every UserName token. Its keys
now ride the deployment artifact instead.

- ConfigComposer snapshots ApiKeys alongside the NodeAcls it already carried.
  Only the peppered HMAC ships, never a secret, and the pepper is node config
  that is deliberately not in the artifact.
- DeploymentArtifact.ParseDataPlaneAuthority decodes both node-side. Grants are
  scoped to the node's own cluster; keys are not, because ApiKey carries no
  ClusterId — a key is a fleet-wide credential and the ACL rows are what bind it.
- OpcUaPublishActor installs them on DataPlaneAuthorityState on every apply,
  BEFORE its plan.IsEmpty early-return: an artifact that only revokes a key
  produces an empty address-space plan, so feeding after that return would leave
  the revoked key working until an unrelated structural change redeployed.
- ArtifactApiKeyStore serves them to session activation; a node with a ConfigDb
  keeps ConfigDbApiKeyStore, whose per-request read is what makes revocation
  immediate there.
- OtOpcUaNodeManager gains DataPlaneAuthority — the cluster identity blocker #4
  named. NodeScope.ClusterId is required and the evaluator fails closed on a
  mismatch, so until now no scope it built could have evaluated. Nothing reads it
  until stages 5/6.

The generation is a node-local COUNTER driven by the RevisionHash, not derived
from its bits. PermissionTrieCache treats the highest GenerationId as current, so
a generation taken from hash bytes would install a lower number about half the
time and the cache would go on serving the previous deployment's ACLs, silently.

Sessions are not stamped with it yet — that belongs with the first seam that
reads a UserAuthorizationState, in stage 5, rather than being built now and
consulted by nothing.

Live-gated on docker-dev against site-a-1 (driver-only, no ConfigDb): key
authenticates, wrong secret denied, both halves of the revocation asymmetry
observed, and a SITE-A grant confirmed not to reach site-b-1. Key minted with an
independent Python HMAC so the verifier was checked against something other than
itself. Rig left clean.

Claude-Session: https://claude.ai/code/session_015p7wGqy3YpZNCpDzTpGMKo

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

@@ -3,6 +3,7 @@ using Opc.Ua;
 using Opc.Ua.Server;
 using ZB.MOM.WW.OtOpcUa.Commons.OpcUa;
 using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+using ZB.MOM.WW.OtOpcUa.Core.Authorization;
 using ZB.MOM.WW.OtOpcUa.OpcUaServer.Security;
 // The SDK's HistoryRead service result (the value the override fills + hands back) and the historian
 // data source's read DTO are both named HistoryReadResult. Alias each to keep the two unambiguous:
@@ -243,6 +244,38 @@ public sealed class OtOpcUaNodeManager : CustomNodeManager2
         set => _historianDataSource = value ?? NullHistorianDataSource.Instance;
     }
 
+    /// <summary>
+    ///     #520 stage 4 — the node's current data-plane authorization inputs: which cluster it serves,
+    ///     the generation those were resolved at, and the ACL grants themselves.
+    /// </summary>
+    /// <remarks>
+    ///     <para>
+    ///         This closes the fourth #520 blocker: <c>NodeScope.ClusterId</c> is <c>required</c> and
+    ///         <c>TriePermissionEvaluator</c> fails closed when it disagrees with the session's, but the
+    ///         node manager had no idea what cluster it was serving — so no <c>NodeScope</c> it built
+    ///         could ever have evaluated. It is fed here rather than at construction because the SDK
+    ///         constructs this manager during <c>StartAsync</c>, before any artifact has been applied,
+    ///         and the value changes on every deploy.
+    ///     </para>
+    ///     <para>
+    ///         Stage 4 only supplies it. The enforcement seams that consume it — the write gate, the alarm
+    ///         gates, HistoryRead, and (stage 6) read/browse/subscribe — land in stages 5 and 6, so
+    ///         nothing reads this yet and authorization behaviour is unchanged.
+    ///     </para>
+    ///     <para>
+    ///         Backed by a <c>volatile</c> field for the same reason as <see cref="HistorianDataSource"/>:
+    ///         written on the deploy path, read on SDK request threads. Assigning <c>null</c> restores the
+    ///         empty source, which authenticates and authorizes nothing.
+    ///     </para>
+    /// </remarks>
+    public IDataPlaneAuthoritySource DataPlaneAuthority
+    {
+        get => _dataPlaneAuthority;
+        set => _dataPlaneAuthority = value ?? EmptyDataPlaneAuthoritySource.Instance;
+    }
+
+    private volatile IDataPlaneAuthoritySource _dataPlaneAuthority = EmptyDataPlaneAuthoritySource.Instance;
+
     /// <summary>
     ///     The upper bound on the bounded over-fetch <see cref="ServeRawPaged"/> uses to page WITHIN an
     ///     oversized "tie cluster" — more raw samples sharing one SourceTimestamp than the client's per-page