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.DeploymentManager/ServiceCollectionExtensions.cs

@@ -21,6 +21,7 @@ public static class ServiceCollectionExtensions
     /// artifact-deployment timeouts are tunable via <c>appsettings.json</c>.
     /// </summary>
     /// <param name="services">The service collection to register into.</param>
+    /// <returns>The <paramref name="services"/> instance for chaining.</returns>
     public static IServiceCollection AddDeploymentManager(this IServiceCollection services)
     {
         // DeploymentManager-008: ensure the options class is always resolvable.
@@ -46,6 +47,7 @@ public static class ServiceCollectionExtensions
     /// Registers Deployment Manager Akka actor bindings. Actor creation is handled by the Host during actor system startup.
     /// </summary>
     /// <param name="services">The service collection to register into.</param>
+    /// <returns>The <paramref name="services"/> instance for chaining.</returns>
     public static IServiceCollection AddDeploymentManagerActors(this IServiceCollection services)
     {
         // Akka actor registration is handled by Host component during actor system startup