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.CLI/Commands/AuditExportHelpers.cs

@@ -74,6 +74,7 @@ public static class AuditExportHelpers
     /// </summary>
     /// <param name="args">The export arguments containing filters and format.</param>
     /// <param name="now">The current time for resolving relative time specifications.</param>
+    /// <returns>The full query string (including the leading <c>?</c>) for the export endpoint.</returns>
     public static string BuildQueryString(AuditExportArgs args, DateTimeOffset now)
     {
         var parts = new List<string>();
@@ -116,6 +117,7 @@ public static class AuditExportHelpers
     /// <param name="args">The export arguments containing filters and output file path.</param>
     /// <param name="output">Text writer for command output messages.</param>
     /// <param name="now">The current time for resolving relative time specifications.</param>
+    /// <returns>0 on success, 1 on general error, or 2 on authorization failure.</returns>
     public static async Task<int> RunExportAsync(
         ManagementHttpClient client, AuditExportArgs args, TextWriter output, DateTimeOffset now)
     {
@@ -178,6 +180,8 @@ public static class AuditExportHelpers
     /// to extract the <c>code</c> field. Returns null if the body is empty, not valid JSON, or
     /// has no <c>code</c> property — callers fall back to "ERROR" in that case.
     /// </summary>
+    /// <param name="body">The HTTP response body string to parse for an error code.</param>
+    /// <returns>The <c>code</c> string from the JSON error envelope, or null if absent or unparseable.</returns>
     internal static string? TryExtractErrorCode(string body)
     {
         if (string.IsNullOrWhiteSpace(body))