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.Commons/Interfaces/Repositories/INotificationRepository.cs

@@ -25,16 +25,19 @@ public interface INotificationRepository
     /// <summary>Adds a new notification list.</summary>
     /// <param name="list">The notification list to add.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task representing the asynchronous operation.</returns>
     Task AddNotificationListAsync(NotificationList list, CancellationToken cancellationToken = default);
 
     /// <summary>Updates an existing notification list.</summary>
     /// <param name="list">The notification list to update.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task representing the asynchronous operation.</returns>
     Task UpdateNotificationListAsync(NotificationList list, CancellationToken cancellationToken = default);
 
     /// <summary>Deletes a notification list by ID.</summary>
     /// <param name="id">The notification list ID.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task representing the asynchronous operation.</returns>
     Task DeleteNotificationListAsync(int id, CancellationToken cancellationToken = default);
 
     // NotificationRecipient
@@ -53,16 +56,19 @@ public interface INotificationRepository
     /// <summary>Adds a new notification recipient.</summary>
     /// <param name="recipient">The recipient to add.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task representing the asynchronous operation.</returns>
     Task AddRecipientAsync(NotificationRecipient recipient, CancellationToken cancellationToken = default);
 
     /// <summary>Updates an existing notification recipient.</summary>
     /// <param name="recipient">The recipient to update.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task representing the asynchronous operation.</returns>
     Task UpdateRecipientAsync(NotificationRecipient recipient, CancellationToken cancellationToken = default);
 
     /// <summary>Deletes a notification recipient by ID.</summary>
     /// <param name="id">The recipient ID.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task representing the asynchronous operation.</returns>
     Task DeleteRecipientAsync(int id, CancellationToken cancellationToken = default);
 
     // SmtpConfiguration
@@ -80,16 +86,19 @@ public interface INotificationRepository
     /// <summary>Adds a new SMTP configuration.</summary>
     /// <param name="configuration">The SMTP configuration to add.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task representing the asynchronous operation.</returns>
     Task AddSmtpConfigurationAsync(SmtpConfiguration configuration, CancellationToken cancellationToken = default);
 
     /// <summary>Updates an existing SMTP configuration.</summary>
     /// <param name="configuration">The SMTP configuration to update.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task representing the asynchronous operation.</returns>
     Task UpdateSmtpConfigurationAsync(SmtpConfiguration configuration, CancellationToken cancellationToken = default);
 
     /// <summary>Deletes an SMTP configuration by ID.</summary>
     /// <param name="id">The SMTP configuration ID.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task representing the asynchronous operation.</returns>
     Task DeleteSmtpConfigurationAsync(int id, CancellationToken cancellationToken = default);
 
     /// <summary>Saves pending changes to the repository.</summary>