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.SiteRuntime/Persistence/SiteStorageInitializer.cs

@@ -23,6 +23,7 @@ public class SiteStorageInitializer : IHostedService
     /// Initializes the SQLite schema before the actor system starts.
     /// </summary>
     /// <param name="cancellationToken">Cancellation token for the startup operation.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     public async Task StartAsync(CancellationToken cancellationToken)
     {
         await _storage.InitializeAsync();
@@ -32,5 +33,6 @@ public class SiteStorageInitializer : IHostedService
     /// No-op stop; schema initialization does not require cleanup.
     /// </summary>
     /// <param name="cancellationToken">Unused cancellation token.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     public Task StopAsync(CancellationToken cancellationToken) => Task.CompletedTask;
 }