Merge origin/main with local pending work and update AGENTS.md references

- Resolve 14 conflicts from popping local stash on top of origin's
  eed1e88 + 8d3352f doc-comment additions (11 mechanical, plus
  version.rs, DashboardAuthenticatorTests.cs, DashboardGalaxyProjector.cs)
- Fix 4 test files that used AGENTS.md as the repo-root sentinel
  (now use CLAUDE.md, since AGENTS.md was removed in 4731ab5)
- Redirect 10 doc citations from AGENTS.md to the matching gateway.md
  sections (Value Model, Status Model, Security, STA Worker Thread
  Model, gRPC Layer rule, cancellation rule)

Verified: solution build clean, x86 worker build clean, 266/266
gateway tests passing, 121/121 worker tests passing.

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

src/MxGateway.Tests/Gateway/Grpc/MxAccessGatewayServiceTests.cs

@@ -237,6 +237,7 @@ public sealed class MxAccessGatewayServiceTests
         return new MxAccessGatewayService(
             sessionManager,
             identityAccessor ?? new GatewayRequestIdentityAccessor(),
+            new AllowAllConstraintEnforcer(),
             new MxAccessGrpcRequestValidator(),
             new MxAccessGrpcMapper(),
             new FakeEventStreamService(sessionManager),
@@ -445,6 +446,35 @@ public sealed class MxAccessGatewayServiceTests
         }
     }
 
+    private sealed class AllowAllConstraintEnforcer : IConstraintEnforcer
+    {
+        public Task<ConstraintFailure?> CheckReadTagAsync(
+            ApiKeyIdentity? identity,
+            string tagAddress,
+            CancellationToken cancellationToken) => Task.FromResult<ConstraintFailure?>(null);
+
+        public Task<ConstraintFailure?> CheckReadHandleAsync(
+            ApiKeyIdentity? identity,
+            GatewaySession session,
+            int serverHandle,
+            int itemHandle,
+            CancellationToken cancellationToken) => Task.FromResult<ConstraintFailure?>(null);
+
+        public Task<ConstraintFailure?> CheckWriteHandleAsync(
+            ApiKeyIdentity? identity,
+            GatewaySession session,
+            int serverHandle,
+            int itemHandle,
+            CancellationToken cancellationToken) => Task.FromResult<ConstraintFailure?>(null);
+
+        public Task RecordDenialAsync(
+            ApiKeyIdentity? identity,
+            string commandKind,
+            string target,
+            ConstraintFailure failure,
+            CancellationToken cancellationToken) => Task.CompletedTask;
+    }
+
     private sealed class FakeWorkerClient(int processId) : IWorkerClient
     {
         /// <inheritdoc />