docs: complete XML doc coverage (returns, summaries, inheritdoc)

Resolve all 622 issues flagged by the enhanced CommentChecker: add missing
<returns> tags (incl. the standard phrasing on non-generic Task methods),
add missing <summary> tags, and replace misused/redundant <inheritdoc/> on
members that override or implement nothing with real documentation.
Documentation-only — no behavior change; solution builds clean.

src/ZB.MOM.WW.ScadaBridge.Host/Health/ActiveNodeGate.cs

@@ -32,11 +32,7 @@ public sealed class ActiveNodeGate : IActiveNodeGate
         _akkaService = akkaService;
     }
 
-    /// <summary>
-    /// <c>true</c> only when this node has joined the cluster (<see cref="MemberStatus.Up"/>)
-    /// AND is the current cluster leader; <c>false</c> in every other state
-    /// (actor system not yet started, node still joining, node is a standby).
-    /// </summary>
+    /// <inheritdoc />
     public bool IsActiveNode
     {
         get

src/ZB.MOM.WW.ScadaBridge.Host/LoggerConfigurationFactory.cs

@@ -52,6 +52,7 @@ public static class LoggerConfigurationFactory
     /// <param name="siteId">Site identifier added as a log enrichment property.</param>
     /// <param name="nodeHostname">Hostname added as a log enrichment property.</param>
     /// <param name="warningWriter">Writer that receives the one-shot Host-020 override-warning when both keys are present.</param>
+    /// <returns>The fully configured <see cref="LoggerConfiguration"/> ready to create the Serilog logger.</returns>
     internal static LoggerConfiguration Build(
         IConfiguration configuration,
         string nodeRole,
@@ -104,6 +105,8 @@ public static class LoggerConfigurationFactory
     /// Null/blank values are treated as "unset" and silently default — only
     /// explicit-but-invalid values trigger the warning.
     /// </summary>
+    /// <param name="level">Configured level string, possibly null/blank/invalid.</param>
+    /// <returns>The parsed <see cref="LogEventLevel"/>, or <see cref="LogEventLevel.Information"/> when the value is absent or unrecognised.</returns>
     internal static LogEventLevel ParseLevel(string? level)
         => ParseLevel(level, Console.Error);
 
@@ -114,6 +117,7 @@ public static class LoggerConfigurationFactory
     /// </summary>
     /// <param name="level">Configured level string, possibly null/blank/invalid.</param>
     /// <param name="warningWriter">Writer that receives a single warning line if the value is non-blank but unparseable.</param>
+    /// <returns>The parsed <see cref="LogEventLevel"/>, or <see cref="LogEventLevel.Information"/> when the value is absent or unrecognised.</returns>
     internal static LogEventLevel ParseLevel(string? level, TextWriter warningWriter)
     {
         if (Enum.TryParse<LogEventLevel>(level, ignoreCase: true, out var parsed))

src/ZB.MOM.WW.ScadaBridge.Host/StartupRetry.cs

@@ -28,6 +28,7 @@ public static class StartupRetry
     /// <param name="logger">Logger for retry warnings.</param>
     /// <param name="isTransient">Optional predicate classifying an exception as transient; null means all exceptions are transient.</param>
     /// <param name="cancellationToken">Cancellation token that aborts the retry loop immediately.</param>
+    /// <returns>A task that completes when the operation succeeds, or faults on a permanent or final-attempt failure.</returns>
     public static Task ExecuteWithRetryAsync(
         string operationName,
         Func<Task> operation,
@@ -45,6 +46,14 @@ public static class StartupRetry
     /// <c>IHostApplicationLifetime.ApplicationStopping</c> inside the operation as well
     /// as inside the inter-attempt <c>Task.Delay</c>.
     /// </summary>
+    /// <param name="operationName">Human-readable name of the operation, used in log messages.</param>
+    /// <param name="operation">The async operation to attempt; receives the cancellation token on each try.</param>
+    /// <param name="maxAttempts">Maximum number of attempts before the exception propagates.</param>
+    /// <param name="initialDelay">Delay before the second attempt; doubled on each subsequent retry, capped at 30 seconds.</param>
+    /// <param name="logger">Logger for retry warnings and success messages.</param>
+    /// <param name="isTransient">Optional predicate classifying an exception as transient; null means all exceptions are transient.</param>
+    /// <param name="cancellationToken">Token to observe for cancellation; aborts the retry loop immediately.</param>
+    /// <returns>A task that completes when the operation succeeds, or faults on a permanent or final-attempt failure.</returns>
     public static async Task ExecuteWithRetryAsync(
         string operationName,
         Func<CancellationToken, Task> operation,
@@ -93,6 +102,7 @@ public static class StartupRetry
     /// permanent and must fail fast).
     /// </summary>
     /// <param name="ex">The exception to classify.</param>
+    /// <returns><c>true</c> if the exception is a transient connection or timeout fault; <c>false</c> otherwise.</returns>
     public static bool IsTransientDatabaseFault(Exception ex)
     {
         // Unwrap a single layer of aggregation so a faulted Task surfaces correctly.