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.Telemetry/src/ZB.MOM.WW.Telemetry.Serilog/ILogRedactor.cs

@@ -11,6 +11,20 @@ public interface ILogRedactor
     /// <summary>
     /// Inspects and mutates the supplied log-event <paramref name="properties"/> in place — remove
     /// or replace any sensitive values. Called on every log event before it reaches any sink.
+    /// Both removing a key (the property is dropped from the event) and replacing its value are
+    /// honoured by <see cref="RedactionEnricher"/>.
+    /// <para>
+    /// <b>Reach — scalar top-level properties only.</b> Each entry's value is the unwrapped scalar
+    /// of a Serilog <c>ScalarValue</c> property (so simple string/number/etc. properties such as
+    /// <c>{apiKey}</c> can be read and masked directly). <b>Destructured / structured properties are
+    /// not unwrapped:</b> a <c>{@Object}</c> property arrives as the raw Serilog
+    /// <c>StructureValue</c> wrapper (and a sequence/dictionary as <c>SequenceValue</c>/
+    /// <c>DictionaryValue</c>). A redactor can therefore replace or remove the <i>whole</i>
+    /// top-level property, but it cannot reach a field <i>nested inside</i> a destructured object to
+    /// mask it selectively. To protect a sensitive field of a logged object, do not destructure it
+    /// (log the field as its own scalar property), or remove/replace the entire structured property
+    /// by key.
+    /// </para>
     /// </summary>
     /// <param name="properties">The mutable property dictionary for the current log event.</param>
     void Redact(IDictionary<string, object?> properties);