Fix all baseline code-review findings across the six shared libraries

Resolves the 35 findings from the 2026-06-01 baseline (commit 26ba1c7),
test-first for every behavioral change. +51 tests (331 -> 382 passing, 0 failed).

- Telemetry-001 (HIGH): RedactionEnricher now honours property removal, so a
  redactor that drops a key actually scrubs the secret from the event.
- Auth: LDAP validator ValidateOnStart; API-key verify no longer fails on a
  best-effort MarkUsed write or a corrupt scopes column (fail-closed); LDAP cert
  validation hook; KeyPrefix persistence aligned; README algorithm corrected.
- Health: Akka checks return Degraded (not throw) when the cluster isn't up yet;
  GrpcDependencyHealthCheck catch-all; null 'description' rendered; composite
  endpoint builder; XML docs shipped.
- Audit: CompositeAuditWriter no longer re-throws OperationCanceledException;
  TruncatingAuditRedactor over-redact scrubs Target + safe negative max; options
  record; XML docs shipped.
- Configuration: TryAddEnumerable idempotent registration; consistent port
  quoting; strict invariant port parsing; XML docs + README packaged.
- Theme: mobile toggle is now CSS-only (no Bootstrap JS); token/CSS hygiene;
  XML docs on the public parameter surface.

Shared-contract/spec docs updated where the code was the source of truth
(observability service.instance.id, MapZbMetrics, redactor reach). All changes
additive/back-compatible at v0.1.0. code-reviews bookkeeping follows separately.

ZB.MOM.WW.Health/tests/ZB.MOM.WW.Health.Akka.Tests/ActiveNodeDecisionTests.cs

@@ -86,6 +86,50 @@ public sealed class ActiveNodeDecisionTests
         Assert.False(gate.IsActiveNode);
     }
 
+    [Fact]
+    public async Task HealthCheck_RoleLess_ClusterInaccessible_ReturnsDegraded()
+    {
+        // ActorSystem present but Akka.Cluster not configured → Cluster.Get throws. The check must
+        // return Degraded (startup-safety rule), not let the exception escape (→ Unhealthy).
+        using var system = ActorSystem.Create("plain-no-cluster-roleless");
+        try
+        {
+            var provider = new ServiceCollection()
+                .AddSingleton(system)
+                .BuildServiceProvider();
+            var check = new ActiveNodeHealthCheck(provider);
+
+            var result = await check.CheckHealthAsync(NewContext(check));
+
+            Assert.Equal(HealthStatus.Degraded, result.Status);
+        }
+        finally
+        {
+            await system.Terminate();
+        }
+    }
+
+    [Fact]
+    public async Task HealthCheck_RoleFiltered_ClusterInaccessible_ReturnsDegraded()
+    {
+        using var system = ActorSystem.Create("plain-no-cluster-rolefiltered");
+        try
+        {
+            var provider = new ServiceCollection()
+                .AddSingleton(system)
+                .BuildServiceProvider();
+            var check = new ActiveNodeHealthCheck(provider, "admin");
+
+            var result = await check.CheckHealthAsync(NewContext(check));
+
+            Assert.Equal(HealthStatus.Degraded, result.Status);
+        }
+        finally
+        {
+            await system.Terminate();
+        }
+    }
+
     private static HealthCheckContext NewContext(IHealthCheck check) => new()
     {
         Registration = new HealthCheckRegistration("active-node", check, HealthStatus.Unhealthy, tags: null),