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.CentralUI/ScriptAnalysis/SandboxHostHelpers.cs

@@ -32,6 +32,7 @@ public class SandboxExternalHelper
     /// <param name="methodName">The method name to invoke.</param>
     /// <param name="parameters">Optional method parameters.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that resolves to the <see cref="ExternalCallResult"/> from the external system.</returns>
     public Task<ExternalCallResult> Call(
         string systemName,
         string methodName,
@@ -49,6 +50,7 @@ public class SandboxExternalHelper
     /// <param name="methodName">The method name to invoke.</param>
     /// <param name="parameters">Optional method parameters.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that resolves to the <see cref="ExternalCallResult"/> from the external system.</returns>
     public Task<ExternalCallResult> CachedCall(
         string systemName,
         string methodName,
@@ -80,6 +82,7 @@ public class SandboxDatabaseHelper
     /// <summary>Gets a database connection by name.</summary>
     /// <param name="name">The database connection name.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that resolves to the open <see cref="DbConnection"/> for the named database.</returns>
     public Task<DbConnection> Connection(string name, CancellationToken cancellationToken = default)
     {
         if (_gateway == null)
@@ -93,6 +96,7 @@ public class SandboxDatabaseHelper
     /// <param name="sql">The SQL statement to execute.</param>
     /// <param name="parameters">Optional SQL parameters.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     public Task CachedWrite(
         string name,
         string sql,
@@ -123,6 +127,7 @@ public class SandboxNotifyHelper
 {
     /// <summary>Selects the notification list to send to.</summary>
     /// <param name="listName">The notification list name.</param>
+    /// <returns>A <see cref="SandboxNotifyTarget"/> for the specified list.</returns>
     public SandboxNotifyTarget To(string listName) =>
         new();
 
@@ -133,6 +138,7 @@ public class SandboxNotifyHelper
     /// <c>NotifyHelper.Status</c>.
     /// </summary>
     /// <param name="notificationId">The notification ID to check status for.</param>
+    /// <returns>A task that resolves to a placeholder <see cref="NotificationDeliveryStatus"/> with status "Unknown".</returns>
     public Task<NotificationDeliveryStatus> Status(string notificationId) =>
         Task.FromResult(new NotificationDeliveryStatus("Unknown", 0, null, null));
 }
@@ -156,6 +162,7 @@ public class SandboxNotifyTarget
     /// <param name="subject">The notification subject.</param>
     /// <param name="message">The notification message.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that resolves to a fake notification ID string (a random GUID).</returns>
     public Task<string> Send(string subject, string message, CancellationToken cancellationToken = default) =>
         Task.FromResult(Guid.NewGuid().ToString("N"));
 }