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.Auth/src/ZB.MOM.WW.Auth.ApiKeys/Admin/ApiKeyAdminCommands.cs

@@ -101,7 +101,10 @@ public sealed class ApiKeyAdminCommands
 
         var record = new ApiKeyRecord(
             KeyId: keyId,
-            KeyPrefix: $"{_options.TokenPrefix}_{keyId}",
+            // KeyPrefix is the bare token prefix (e.g. "mxgw"), NOT prefix_keyId — the key id is
+            // already its own column. Embedding it here produced a self-referential value that
+            // confused admin tooling and disagreed with the read/test paths (see Auth-005).
+            KeyPrefix: _options.TokenPrefix,
             SecretHash: secretHash,
             DisplayName: displayName,
             Scopes: scopes,

ZB.MOM.WW.Auth/src/ZB.MOM.WW.Auth.ApiKeys/ApiKeyVerifier.cs

@@ -62,8 +62,24 @@ public sealed class ApiKeyVerifier(
             return Fail(ApiKeyFailure.SecretMismatch);
         }
 
-        // 6. Record successful use, then return the identity (no secret/hash/pepper included).
-        await store.MarkUsedAsync(record.KeyId, _timeProvider.GetUtcNow(), ct).ConfigureAwait(false);
+        // 6. The authentication decision is already made (line 60). Recording last-used is
+        //    best-effort bookkeeping: a transient storage hiccup (SQLITE_BUSY past the busy-timeout,
+        //    disk full, DB locked by a migration) must NOT turn an otherwise-valid credential into a
+        //    failed auth. Swallow any non-cancellation failure so the only exception path remains
+        //    cancellation, as the class contract promises. Cancellation is honoured (re-thrown).
+        try
+        {
+            await store.MarkUsedAsync(record.KeyId, _timeProvider.GetUtcNow(), ct).ConfigureAwait(false);
+        }
+        catch (OperationCanceledException)
+        {
+            throw;
+        }
+        catch
+        {
+            // Best-effort: the last-used write failed, but the credential is valid. Fail open on the
+            // bookkeeping (not the auth decision) rather than denying a legitimate caller.
+        }
 
         return new ApiKeyVerification(
             Succeeded: true,

ZB.MOM.WW.Auth/src/ZB.MOM.WW.Auth.ApiKeys/Sqlite/ScopeSerializer.cs

@@ -20,7 +20,12 @@ public static class ScopeSerializer
 
     /// <summary>Deserializes scopes from a JSON array string.</summary>
     /// <param name="value">The JSON string to deserialize; may be null or empty.</param>
-    /// <returns>An ordinal-compared set of scopes; empty when the input is null/blank.</returns>
+    /// <returns>
+    /// An ordinal-compared set of scopes; empty when the input is null/blank. A malformed or
+    /// non-array column (operator tampering, a partial write, a format change, or a buggy writer)
+    /// fails closed to an EMPTY set rather than throwing, so a single poisoned row degrades to a
+    /// zero-scope identity on the auth path instead of an unhandled <see cref="JsonException"/>.
+    /// </returns>
     public static IReadOnlySet<string> Deserialize(string? value)
     {
         if (string.IsNullOrWhiteSpace(value))
@@ -28,7 +33,18 @@ public static class ScopeSerializer
             return new HashSet<string>(StringComparer.Ordinal);
         }
 
-        string[]? scopes = JsonSerializer.Deserialize<string[]>(value);
+        string[]? scopes;
+        try
+        {
+            scopes = JsonSerializer.Deserialize<string[]>(value);
+        }
+        catch (JsonException)
+        {
+            // Fail closed: a corrupt scopes column yields no scopes rather than an exception on the
+            // verification hot path. The verifier's "only exception path is cancellation" contract
+            // is preserved, and a key with an unreadable scope set is left with zero authority.
+            return new HashSet<string>(StringComparer.Ordinal);
+        }
 
         return new HashSet<string>(scopes ?? [], StringComparer.Ordinal);
     }