feat(security): enforce node ACLs on write, alarms and HistoryRead (#520 stage 5)

`Security:Acl:Enabled` (default false) makes scoped `NodeAcl` grants decide
data-plane authorization at the three seams that have one, and gives HistoryRead
a check it never had. Read, Browse and Subscribe stay ungated — stage 6.

The ACL decision REPLACES the server-wide role check rather than chaining with
it. Chained, a grant would have to confer the role as well as pass the scope
check, and only Cluster-scoped grants confer a role — so every narrow grant
would have stayed inert and the flag would have looked inert too. The
load-bearing test is an ALLOW: a session carrying no roles at all writing
successfully on the strength of its grant. A deny-only test passes against a
build where the ACL is never consulted, because the role gate denies too.

Found en route: the principal never reached the session. The authenticator
passed it as OpcUaUserAuthResult.DisplayName, but RoleCarryingUserIdentity
derives DisplayName from the presented token — for a key-bearing client that is
the static username `apikey`, identical fleet-wide. So the trie's matching key
was dropped at the identity boundary, and the audit ClientUserId on a rejected
write recorded `apikey` for every consuming system. Principal and ApiKeyId are
now carried explicitly.

Beyond the stage as sketched:

- Revocation reaches an OPEN session. Every decision re-checks the
  authenticating key against the current snapshot; without it a key revoked by a
  deployment kept its authority until the client chose to reconnect, which for a
  machine-to-machine consumer can be indefinitely.
- UserAuthorizationState is built per CALL, not per session. The per-session
  shape exists so an LDAP session can re-resolve membership that changed out of
  band; nothing can change out of band under API keys, so the generation stamp is
  the whole invalidation signal and a per-call record picks it up for free.
  IsStale/NeedsRefresh therefore cannot fire here and are documented as vestigial.
- The trie is built inside DataPlaneAuthorityState.Apply, under the same
  generation as the snapshot, rather than by a second wiring at the publish
  actor. An uninstalled trie denies everything — indistinguishable from working
  enforcement. Deleting the install turns 13 of the 22 new tests red.
- The deploy log reports what the BUILD dropped instead of re-deriving it. The
  old count agreed with the builder on one of its four drop reasons; a rule with
  a blank ScopeId, a retired scope kind, or a path not starting at a realm
  vanished with the log reading zero.

Both IApiKeyStore implementations widened to the full grant set. The narrowing
was redundant — ApiKeyInterimRoleMapper applies the same filter itself — and
became a trap once scope was enforced. Pinned by asserting the roles are
unchanged, with the two grants carrying different flags so it cannot pass by
accident.

Falsified by mutation: enforcement never engaging, the write seam ignoring the
ACL, the realm dropped from the scope, the revocation check removed, and the
trie never installed each turn the intended tests red and no others.

Full solution suite green.

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

src/Server/ZB.MOM.WW.OtOpcUa.Host/OpcUa/ConfigDbApiKeyStore.cs

@@ -104,24 +104,34 @@ public sealed class ConfigDbApiKeyStore : IApiKeyStore
 
         if (key is null) return null;
 
-        return new ApiKeyLookup(key, await LoadClusterGrantsAsync(db, key.Principal, ct).ConfigureAwait(false));
+        return new ApiKeyLookup(key, await LoadGrantsAsync(db, key.Principal, ct).ConfigureAwait(false));
     }
 
     /// <inheritdoc />
     public async Task<IReadOnlyList<NodeAcl>> FindGrantsAsync(string principal, CancellationToken ct)
     {
         await using var db = await _factory.CreateDbContextAsync(ct).ConfigureAwait(false);
-        return await LoadClusterGrantsAsync(db, principal, ct).ConfigureAwait(false);
+        return await LoadGrantsAsync(db, principal, ct).ConfigureAwait(false);
     }
 
-    private async Task<IReadOnlyList<NodeAcl>> LoadClusterGrantsAsync(
+    /// <summary>Loads a principal's grants, confined to this node's cluster.</summary>
+    /// <remarks>
+    ///     <b>The full grant set, not just the <c>Cluster</c>-scoped rows</b> (#520 stage 5). The old
+    ///     narrowing existed because only cluster-scoped rows could confer an interim role, but
+    ///     <see cref="ApiKeyInterimRoleMapper"/> applies that same filter itself, so it was redundant even
+    ///     then — and once scope is enforced it becomes a trap, silently truncating what
+    ///     <c>ApiKeyLookup.Grants</c> claims to be. Removing it changes no role.
+    /// </remarks>
+    /// <param name="db">The config database.</param>
+    /// <param name="principal">The principal to load grants for.</param>
+    /// <param name="ct">The cancellation token.</param>
+    /// <returns>The principal's grants in this node's cluster.</returns>
+    private async Task<IReadOnlyList<NodeAcl>> LoadGrantsAsync(
         OtOpcUaConfigDbContext db, string principal, CancellationToken ct)
     {
-        // Only cluster-scoped rows can confer an interim role (see ApiKeyInterimRoleMapper), so only
-        // those are fetched. Stage 5 widens this to the full grant set for per-node evaluation.
         var rows = await db.NodeAcls
             .AsNoTracking()
-            .Where(a => a.Principal == principal && a.ScopeKind == NodeAclScopeKind.Cluster)
+            .Where(a => a.Principal == principal)
             .ToListAsync(ct)
             .ConfigureAwait(false);