Phase 6.2 Stream B — permission-trie evaluator in Core.Authorization

Ships Stream B.1-B.6 — the data-plane authorization engine Phase 6.2 runs on.
Integration into OPC UA dispatch (Stream C — Read / Write / HistoryRead /
Subscribe / Browse / Call etc.) is the next PR on this branch.

New Core.Abstractions:
- OpcUaOperation enum enumerates every OPC UA surface the evaluator gates:
  Browse, Read, WriteOperate/Tune/Configure (split by SecurityClassification),
  HistoryRead, HistoryUpdate, CreateMonitoredItems, TransferSubscriptions,
  Call, AlarmAcknowledge/Confirm/Shelve. Stream C maps each one back to its
  dispatch call site.

New Core.Authorization namespace:
- NodeScope record + NodeHierarchyKind — 6-level scope addressing for
  Equipment-kind (UNS) namespaces, folder-segment walk for SystemPlatform-kind
  (Galaxy). NodeScope carries a Kind selector so the evaluator knows which
  hierarchy to descend.
- AuthorizationDecision { Verdict, Provenance } + AuthorizationVerdict
  {Allow, NotGranted, Denied} + MatchedGrant. Tri-state per decision #149;
  Phase 6.2 only produces Allow + NotGranted, Denied stays reserved for v2.1
  Explicit Deny without API break.
- IPermissionEvaluator.Authorize(session, operation, scope).
- PermissionTrie + PermissionTrieNode + TrieGrant. In-memory trie keyed on
  the ACL scope hierarchy. CollectMatches walks Cluster → Namespace →
  UnsArea → UnsLine → Equipment → Tag (or → FolderSegment(s) → Tag on
  Galaxy). Pure additive union — matches that share an LDAP group with the
  session contribute flags; OR across levels.
- PermissionTrieBuilder static factory. Build(clusterId, generationId, rows,
  scopePaths?) returns a trie for one generation. Cross-cluster rows are
  filtered out so the trie is cluster-coherent. Stream C follow-up wires a
  real scopePaths lookup from the live DB; tests supply hand-built paths.
- PermissionTrieCache — process-singleton, keyed on (ClusterId, GenerationId).
  Install(trie) adds a generation + promotes to "current" when the id is
  highest-known (handles out-of-order installs gracefully). Prior generations
  retained so an in-flight request against a prior trie still succeeds; GC
  via Prune(cluster, keepLatest).
- UserAuthorizationState — per-session cache of resolved LDAP groups +
  AuthGenerationId + MembershipVersion + MembershipResolvedUtc. Bounded by
  MembershipFreshnessInterval (default 15 min per decision #151) +
  AuthCacheMaxStaleness (default 5 min per decision #152).
- TriePermissionEvaluator — default IPermissionEvaluator. Fails closed on
  stale sessions (IsStale check short-circuits to NotGranted), on cross-
  cluster requests, on empty trie cache. Maps OpcUaOperation → NodePermissions
  via MapOperationToPermission (total — every enum value has a mapping; tested).

Tests (27 new, all pass):
- PermissionTrieTests (7): cluster-level grant cascades to every tag;
  equipment-level grant doesn't leak to sibling equipment; multi-group union
  ORs flags; no-matching-group returns empty; Galaxy folder-segment grant
  doesn't leak to sibling folder; cross-cluster rows don't land in this
  cluster's trie; build is idempotent (B.6 invariants).
- TriePermissionEvaluatorTests (8): allow when flag matches; NotGranted when
  no matching group; NotGranted when flags insufficient; HistoryRead requires
  its own bit (decision-level requirement); cross-cluster session denied;
  stale session fails closed; no cached trie denied; MapOperationToPermission
  is total across every OpcUaOperation.
- PermissionTrieCacheTests (8): empty cache returns null; install-then-get
  round-trips; new generation becomes current; out-of-order install doesn't
  downgrade current; invalidate drops one cluster; prune retains most recent;
  prune no-op when fewer than keep; cluster isolation.
- UserAuthorizationStateTests (4): fresh is not stale; IsStale after 5 min
  default; NeedsRefresh true between freshness + staleness windows.

Full solution dotnet test: 1078 passing (baseline 906, Phase 6.1 = 1042,
Phase 6.2 Stream A = +9, Stream B = +27 = 1078). Pre-existing Client.CLI
Subscribe flake unchanged.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/ZB.MOM.WW.OtOpcUa.Core.Abstractions/OpcUaOperation.cs

@@ -0,0 +1,59 @@
+namespace ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+
+/// <summary>
+///     Every OPC UA operation surface the Phase 6.2 authorization evaluator gates, per
+///     <c>docs/v2/implementation/phase-6-2-authorization-runtime.md</c> §Stream C and
+///     decision #143. The evaluator maps each operation onto the corresponding
+///     <c>NodePermissions</c> bit(s) to decide whether the calling session is allowed.
+/// </summary>
+/// <remarks>
+///     Write is split out into <see cref="WriteOperate"/> / <see cref="WriteTune"/> /
+///     <see cref="WriteConfigure"/> because the underlying driver-reported
+///     <see cref="SecurityClassification"/> already carries that distinction — the
+///     evaluator maps the requested tag's security class to the matching operation value
+///     before checking the permission bit.
+/// </remarks>
+public enum OpcUaOperation
+{
+    /// <summary>
+    ///     <c>Browse</c> + <c>TranslateBrowsePathsToNodeIds</c>. Ancestor visibility implied
+    ///     when any descendant has a grant; denied ancestors filter from browse results.
+    /// </summary>
+    Browse,
+
+    /// <summary><c>Read</c> on a variable node.</summary>
+    Read,
+
+    /// <summary><c>Write</c> when the target has <see cref="SecurityClassification.Operate"/> / <see cref="SecurityClassification.FreeAccess"/>.</summary>
+    WriteOperate,
+
+    /// <summary><c>Write</c> when the target has <see cref="SecurityClassification.Tune"/>.</summary>
+    WriteTune,
+
+    /// <summary><c>Write</c> when the target has <see cref="SecurityClassification.Configure"/>.</summary>
+    WriteConfigure,
+
+    /// <summary><c>HistoryRead</c> — uses its own <c>NodePermissions.HistoryRead</c> bit; Read alone is NOT sufficient (decision in Phase 6.2 Compliance).</summary>
+    HistoryRead,
+
+    /// <summary><c>HistoryUpdate</c> — annotation / insert / delete on historian.</summary>
+    HistoryUpdate,
+
+    /// <summary><c>CreateMonitoredItems</c>. Per-item denial in mixed-authorization batches.</summary>
+    CreateMonitoredItems,
+
+    /// <summary><c>TransferSubscriptions</c>. Re-evaluates transferred items against current auth state.</summary>
+    TransferSubscriptions,
+
+    /// <summary><c>Call</c> on a Method node.</summary>
+    Call,
+
+    /// <summary>Alarm <c>Acknowledge</c>.</summary>
+    AlarmAcknowledge,
+
+    /// <summary>Alarm <c>Confirm</c>.</summary>
+    AlarmConfirm,
+
+    /// <summary>Alarm <c>Shelve</c> / <c>Unshelve</c>.</summary>
+    AlarmShelve,
+}