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.Tests/TierMappingTests.cs

@@ -127,6 +127,31 @@ public sealed class TierMappingTests
         Assert.Equal(0, active.Invocations);
     }
 
+    [Fact]
+    public async Task ChainedConvention_AppliesToAllThreeEndpoints()
+    {
+        // MapZbHealth returns a composite builder, so a convention chained onto its result
+        // (.RequireHost) must gate all three endpoints — not just readiness. With a host filter
+        // that does not match the default test-client host, every tier returns 404.
+        var builder = WebApplication.CreateBuilder();
+        builder.WebHost.UseTestServer();
+        builder.Services.AddHealthChecks()
+            .AddCheck("ready-check", new RecordingHealthCheck(HealthStatus.Healthy), tags: new[] { ZbHealthTags.Ready })
+            .AddCheck("active-check", new RecordingHealthCheck(HealthStatus.Healthy), tags: new[] { ZbHealthTags.Active });
+
+        await using var app = builder.Build();
+        app.MapZbHealth().RequireHost("health.internal");
+        await app.StartAsync();
+
+        var client = app.GetTestClient();
+
+        // The default test host does not match "health.internal", so the convention removed every
+        // endpoint from this host — confirming it fanned out to all three, not just readiness.
+        Assert.Equal(HttpStatusCode.NotFound, (await client.GetAsync("/health/ready")).StatusCode);
+        Assert.Equal(HttpStatusCode.NotFound, (await client.GetAsync("/health/active")).StatusCode);
+        Assert.Equal(HttpStatusCode.NotFound, (await client.GetAsync("/healthz")).StatusCode);
+    }
+
     [Fact]
     public async Task Options_OverrideRoutePaths()
     {