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.ManagementService/ManagementEndpoints.cs

@@ -24,6 +24,7 @@ public static class ManagementEndpoints
     /// zero/negative timeout would make every management call fail immediately.
     /// </summary>
     /// <param name="options">The management service options, or <c>null</c> if not configured.</param>
+    /// <returns>The configured timeout, or <see cref="DefaultAskTimeout"/> when none is set.</returns>
     public static TimeSpan ResolveAskTimeout(ManagementServiceOptions? options)
     {
         if (options is { CommandTimeout: { Ticks: > 0 } configured })
@@ -33,6 +34,7 @@ public static class ManagementEndpoints
 
     /// <summary>Registers the <c>POST /management</c> endpoint on the given route builder.</summary>
     /// <param name="endpoints">The route builder to add the endpoint to.</param>
+    /// <returns>The same <paramref name="endpoints"/> instance for chaining.</returns>
     public static IEndpointRouteBuilder MapManagementAPI(this IEndpointRouteBuilder endpoints)
     {
         endpoints.MapPost("/management", (Delegate)HandleRequest);
@@ -166,9 +168,11 @@ public static class ManagementEndpoints
     {
         /// <summary>Creates a successful parse result wrapping the given command.</summary>
         /// <param name="command">The strongly-typed command object that was parsed.</param>
+        /// <returns>A successful <see cref="CommandParseResult"/> containing the parsed command.</returns>
         public static CommandParseResult Ok(object command) => new(true, command, null, null);
         /// <summary>Creates a failed parse result with the given error message.</summary>
         /// <param name="message">Human-readable description of the parse failure.</param>
+        /// <returns>A failed <see cref="CommandParseResult"/> with the error message and <c>BAD_REQUEST</c> code.</returns>
         public static CommandParseResult Fail(string message) => new(false, null, message, "BAD_REQUEST");
     }
 
@@ -179,6 +183,7 @@ public static class ManagementEndpoints
     /// case does not allocate a throwaway document (finding ManagementService-006).
     /// </summary>
     /// <param name="body">The raw JSON request body string.</param>
+    /// <returns>A <see cref="CommandParseResult"/> with the deserialized command on success, or an error on failure.</returns>
     public static CommandParseResult ParseCommand(string body)
     {
         using JsonDocument doc = ParseDocument(body, out var parseError);