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/DeploymentService.cs

@@ -137,6 +137,7 @@ public class DeploymentService
     /// <param name="instanceId">The database ID of the instance to deploy.</param>
     /// <param name="user">The username initiating the deployment, recorded in the audit log.</param>
     /// <param name="cancellationToken">Cancellation token for the operation.</param>
+    /// <returns>A task that resolves to a success result containing the deployment record, or a failure result with an error message.</returns>
     public async Task<Result<DeploymentRecord>> DeployInstanceAsync(
         int instanceId,
         string user,
@@ -335,6 +336,7 @@ public class DeploymentService
     /// <param name="instanceId">The database ID of the instance to disable.</param>
     /// <param name="user">The username initiating the operation, recorded in the audit log.</param>
     /// <param name="cancellationToken">Cancellation token for the operation.</param>
+    /// <returns>A task that resolves to a success result with the site response, or a failure result with an error message.</returns>
     public async Task<Result<InstanceLifecycleResponse>> DisableInstanceAsync(
         int instanceId,
         string user,
@@ -404,6 +406,7 @@ public class DeploymentService
     /// <param name="instanceId">The database ID of the instance to enable.</param>
     /// <param name="user">The username initiating the operation, recorded in the audit log.</param>
     /// <param name="cancellationToken">Cancellation token for the operation.</param>
+    /// <returns>A task that resolves to a success result with the site response, or a failure result with an error message.</returns>
     public async Task<Result<InstanceLifecycleResponse>> EnableInstanceAsync(
         int instanceId,
         string user,
@@ -472,6 +475,7 @@ public class DeploymentService
     /// <param name="instanceId">The database ID of the instance to delete.</param>
     /// <param name="user">The username initiating the deletion, recorded in the audit log.</param>
     /// <param name="cancellationToken">Cancellation token for the operation.</param>
+    /// <returns>A task that resolves to a success result with the site response, or a failure result with an error message.</returns>
     public async Task<Result<InstanceLifecycleResponse>> DeleteInstanceAsync(
         int instanceId,
         string user,
@@ -568,6 +572,7 @@ public class DeploymentService
     /// </summary>
     /// <param name="instanceId">The database ID of the instance to compare.</param>
     /// <param name="cancellationToken">Cancellation token for the operation.</param>
+    /// <returns>A task that resolves to a success result with the comparison, or a failure result if no snapshot exists.</returns>
     public async Task<Result<DeploymentComparisonResult>> GetDeploymentComparisonAsync(
         int instanceId,
         CancellationToken cancellationToken = default)
@@ -636,6 +641,7 @@ public class DeploymentService
     /// </summary>
     /// <param name="deploymentId">The unique deployment identifier to look up.</param>
     /// <param name="cancellationToken">Cancellation token for the operation.</param>
+    /// <returns>A task that resolves to the matching deployment record, or null if none exists.</returns>
     public async Task<DeploymentRecord?> GetDeploymentStatusAsync(
         string deploymentId,
         CancellationToken cancellationToken = default)

src/ZB.MOM.WW.ScadaBridge.DeploymentManager/DeploymentStatusNotifier.cs

@@ -22,7 +22,7 @@ public sealed class DeploymentStatusNotifier : IDeploymentStatusNotifier
         _logger = logger;
     }
 
-    /// <inheritdoc />
+    /// <summary>Raised after each call to <see cref="NotifyStatusChanged"/> to broadcast a deployment status change to all registered subscribers.</summary>
     public event Action<DeploymentStatusChange>? StatusChanged;
 
     /// <inheritdoc />

src/ZB.MOM.WW.ScadaBridge.DeploymentManager/IFlatteningPipeline.cs

@@ -15,6 +15,7 @@ public interface IFlatteningPipeline
     /// </summary>
     /// <param name="instanceId">Id of the instance to flatten and validate.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that resolves to the flattened configuration, revision hash, and validation result; or a failure result if flattening could not complete.</returns>
     Task<Result<FlatteningPipelineResult>> FlattenAndValidateAsync(
         int instanceId,
         CancellationToken cancellationToken = default);

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

src/ZB.MOM.WW.ScadaBridge.DeploymentManager/StateTransitionValidator.cs

@@ -18,21 +18,25 @@ public static class StateTransitionValidator
 {
     /// <summary>Returns true when a deploy operation is allowed from the given state.</summary>
     /// <param name="currentState">The current instance state.</param>
+    /// <returns><see langword="true"/> if deploy is permitted; otherwise <see langword="false"/>.</returns>
     public static bool CanDeploy(InstanceState currentState) =>
         currentState is InstanceState.NotDeployed or InstanceState.Enabled or InstanceState.Disabled;
 
     /// <summary>Returns true when a disable operation is allowed from the given state.</summary>
     /// <param name="currentState">The current instance state.</param>
+    /// <returns><see langword="true"/> if disable is permitted; otherwise <see langword="false"/>.</returns>
     public static bool CanDisable(InstanceState currentState) =>
         currentState == InstanceState.Enabled;
 
     /// <summary>Returns true when an enable operation is allowed from the given state.</summary>
     /// <param name="currentState">The current instance state.</param>
+    /// <returns><see langword="true"/> if enable is permitted; otherwise <see langword="false"/>.</returns>
     public static bool CanEnable(InstanceState currentState) =>
         currentState == InstanceState.Disabled;
 
     /// <summary>Returns true when a delete operation is allowed from the given state.</summary>
     /// <param name="currentState">The current instance state.</param>
+    /// <returns><see langword="true"/> if delete is permitted; otherwise <see langword="false"/>.</returns>
     public static bool CanDelete(InstanceState currentState) =>
         currentState is InstanceState.NotDeployed or InstanceState.Enabled or InstanceState.Disabled;
 
@@ -41,6 +45,7 @@ public static class StateTransitionValidator
     /// </summary>
     /// <param name="currentState">The current instance state.</param>
     /// <param name="operation">The operation name to validate (e.g. "deploy", "disable", "enable", "delete").</param>
+    /// <returns>An error message string if the transition is invalid; null if it is permitted.</returns>
     public static string? ValidateTransition(InstanceState currentState, string operation)
     {
         var allowed = operation.ToLowerInvariant() switch