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.TemplateEngine/Services/AreaService.cs

@@ -35,6 +35,7 @@ public class AreaService
     /// <param name="parentAreaId">Optional parent area identifier for hierarchical organization.</param>
     /// <param name="user">The user performing the action for audit logging.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that resolves to a success result containing the new area, or a failure result with an error message.</returns>
     public async Task<Result<Area>> CreateAreaAsync(
         string name, int siteId, int? parentAreaId, string user,
         CancellationToken cancellationToken = default)
@@ -81,6 +82,7 @@ public class AreaService
     /// <param name="name">The new name for the area.</param>
     /// <param name="user">The user performing the action for audit logging.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that resolves to a success result containing the updated area, or a failure result with an error message.</returns>
     public async Task<Result<Area>> UpdateAreaAsync(
         int areaId, string name, string user,
         CancellationToken cancellationToken = default)
@@ -118,6 +120,7 @@ public class AreaService
     /// <param name="newParentAreaId">The new parent area identifier, or null to move to site root.</param>
     /// <param name="user">The user performing the action for audit logging.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that resolves to a success result containing the moved area, or a failure result with an error message.</returns>
     public async Task<Result<Area>> MoveAreaAsync(
         int areaId, int? newParentAreaId, string user,
         CancellationToken cancellationToken = default)
@@ -175,6 +178,7 @@ public class AreaService
     /// <param name="areaId">The area identifier.</param>
     /// <param name="user">The user performing the action for audit logging.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that resolves to a success result with <c>true</c>, or a failure result if deletion is blocked.</returns>
     public async Task<Result<bool>> DeleteAreaAsync(
         int areaId, string user,
         CancellationToken cancellationToken = default)
@@ -224,6 +228,7 @@ public class AreaService
     /// </summary>
     /// <param name="siteId">The site identifier.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that resolves to a read-only list of all areas for the site.</returns>
     public async Task<IReadOnlyList<Area>> GetAreasBySiteIdAsync(int siteId, CancellationToken cancellationToken = default) =>
         await _repository.GetAreasBySiteIdAsync(siteId, cancellationToken);
 
@@ -232,6 +237,7 @@ public class AreaService
     /// </summary>
     /// <param name="areaId">The area identifier.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that resolves to the matching area, or null if not found.</returns>
     public async Task<Area?> GetAreaByIdAsync(int areaId, CancellationToken cancellationToken = default) =>
         await _repository.GetAreaByIdAsync(areaId, cancellationToken);
 

src/ZB.MOM.WW.ScadaBridge.TemplateEngine/Services/SiteService.cs

@@ -112,11 +112,13 @@ public class SiteService
     /// <summary>Returns the site with the given primary key, or <c>null</c> if not found.</summary>
     /// <param name="siteId">Primary key of the site.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that resolves to the matching <see cref="Site"/>, or <c>null</c> if not found.</returns>
     public async Task<Site?> GetSiteByIdAsync(int siteId, CancellationToken cancellationToken = default) =>
         await _repository.GetSiteByIdAsync(siteId, cancellationToken);
 
     /// <summary>Returns all sites.</summary>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that resolves to the complete list of all sites.</returns>
     public async Task<IReadOnlyList<Site>> GetAllSitesAsync(CancellationToken cancellationToken = default) =>
         await _repository.GetAllSitesAsync(cancellationToken);
 

src/ZB.MOM.WW.ScadaBridge.TemplateEngine/Services/TemplateDeletionService.cs

@@ -30,6 +30,7 @@ public class TemplateDeletionService
     /// </summary>
     /// <param name="templateId">The id of the template to check.</param>
     /// <param name="cancellationToken">Cancellation token for the operation.</param>
+    /// <returns>A task that resolves to a successful result if the template can be deleted, or a failure with blocking reasons.</returns>
     public async Task<Result<bool>> CanDeleteTemplateAsync(int templateId, CancellationToken cancellationToken = default)
     {
         var template = await _repository.GetTemplateByIdAsync(templateId, cancellationToken);
@@ -106,6 +107,7 @@ public class TemplateDeletionService
     /// </summary>
     /// <param name="templateId">The id of the template to delete.</param>
     /// <param name="cancellationToken">Cancellation token for the operation.</param>
+    /// <returns>A task that resolves to a successful result when deleted, or a failure with the blocking reason.</returns>
     public async Task<Result<bool>> DeleteTemplateAsync(int templateId, CancellationToken cancellationToken = default)
     {
         var canDelete = await CanDeleteTemplateAsync(templateId, cancellationToken);

src/ZB.MOM.WW.ScadaBridge.TemplateEngine/Services/TemplateFolderService.cs

@@ -28,6 +28,7 @@ public class TemplateFolderService
     /// <param name="parentFolderId">Parent folder id, or null to create at root level.</param>
     /// <param name="user">Username of the actor performing the operation (for audit).</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that resolves to the created <see cref="TemplateFolder"/>, or a failure result if validation fails.</returns>
     public async Task<Result<TemplateFolder>> CreateFolderAsync(
         string name, int? parentFolderId, string user,
         CancellationToken cancellationToken = default)
@@ -62,6 +63,7 @@ public class TemplateFolderService
     /// <param name="newName">New display name for the folder.</param>
     /// <param name="user">Username of the actor performing the operation (for audit).</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that resolves to the updated <see cref="TemplateFolder"/>, or a failure result if the folder is not found or the name collides.</returns>
     public async Task<Result<TemplateFolder>> RenameFolderAsync(
         int folderId, string newName, string user,
         CancellationToken cancellationToken = default)
@@ -94,6 +96,7 @@ public class TemplateFolderService
     /// <param name="newParentId">Target parent folder id, or null to move to root level.</param>
     /// <param name="user">Username of the actor performing the operation (for audit).</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that resolves to the moved <see cref="TemplateFolder"/>, or a failure result if a cycle or name collision is detected.</returns>
     public async Task<Result<TemplateFolder>> MoveFolderAsync(
         int folderId, int? newParentId, string user,
         CancellationToken cancellationToken = default)
@@ -155,6 +158,7 @@ public class TemplateFolderService
     /// <param name="folderId">Id of the folder to delete.</param>
     /// <param name="user">Username of the actor performing the operation (for audit).</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that resolves to a success result if the folder was deleted, or a failure result if the folder is not found or not empty.</returns>
     public async Task<Result<bool>> DeleteFolderAsync(
         int folderId, string user,
         CancellationToken cancellationToken = default)