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.Commons/Interfaces/Repositories/ISiteRepository.cs

@@ -12,59 +12,73 @@ public interface ISiteRepository
     /// <summary>Retrieves a site by its ID.</summary>
     /// <param name="id">The site primary key.</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>
     Task<Site?> GetSiteByIdAsync(int id, CancellationToken cancellationToken = default);
     /// <summary>Retrieves a site by its identifier.</summary>
     /// <param name="siteIdentifier">The unique site identifier string.</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>
     Task<Site?> GetSiteByIdentifierAsync(string siteIdentifier, CancellationToken cancellationToken = default);
     /// <summary>Retrieves all sites.</summary>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that resolves to a read-only list of all <see cref="Site"/> entities.</returns>
     Task<IReadOnlyList<Site>> GetAllSitesAsync(CancellationToken cancellationToken = default);
     /// <summary>Adds a new site.</summary>
     /// <param name="site">The site entity to add.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     Task AddSiteAsync(Site site, CancellationToken cancellationToken = default);
     /// <summary>Updates an existing site.</summary>
     /// <param name="site">The site entity with updated values.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     Task UpdateSiteAsync(Site site, CancellationToken cancellationToken = default);
     /// <summary>Deletes a site.</summary>
     /// <param name="id">The site primary key.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     Task DeleteSiteAsync(int id, CancellationToken cancellationToken = default);
 
     // Data Connections
     /// <summary>Retrieves a data connection by its ID.</summary>
     /// <param name="id">The data connection primary key.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that resolves to the matching <see cref="DataConnection"/>, or <c>null</c> if not found.</returns>
     Task<DataConnection?> GetDataConnectionByIdAsync(int id, CancellationToken cancellationToken = default);
     /// <summary>Retrieves all data connections.</summary>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that resolves to a read-only list of all <see cref="DataConnection"/> entities.</returns>
     Task<IReadOnlyList<DataConnection>> GetAllDataConnectionsAsync(CancellationToken cancellationToken = default);
     /// <summary>Retrieves all data connections for a site.</summary>
     /// <param name="siteId">The site primary key to filter by.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that resolves to a read-only list of <see cref="DataConnection"/> entities for the given site.</returns>
     Task<IReadOnlyList<DataConnection>> GetDataConnectionsBySiteIdAsync(int siteId, CancellationToken cancellationToken = default);
     /// <summary>Adds a new data connection.</summary>
     /// <param name="connection">The data connection entity to add.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     Task AddDataConnectionAsync(DataConnection connection, CancellationToken cancellationToken = default);
     /// <summary>Updates an existing data connection.</summary>
     /// <param name="connection">The data connection entity with updated values.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     Task UpdateDataConnectionAsync(DataConnection connection, CancellationToken cancellationToken = default);
     /// <summary>Deletes a data connection.</summary>
     /// <param name="id">The data connection primary key.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     Task DeleteDataConnectionAsync(int id, CancellationToken cancellationToken = default);
 
     // Instances (for deletion constraint checks)
     /// <summary>Retrieves all instances deployed to a site.</summary>
     /// <param name="siteId">The site primary key to filter by.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that resolves to a read-only list of <see cref="Instance"/> entities for the given site.</returns>
     Task<IReadOnlyList<Instance>> GetInstancesBySiteIdAsync(int siteId, CancellationToken cancellationToken = default);
 
     /// <summary>Saves all pending changes to the database.</summary>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that resolves to the number of state entries written to the database.</returns>
     Task<int> SaveChangesAsync(CancellationToken cancellationToken = default);
 }