refactor(sql): promote the single-row limit onto ISqlDialect

Claude-Session: https://claude.ai/code/session_01GASWkNEi68FSCtvr6rLoEW

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Sql/SqlServerDialect.cs

@@ -29,6 +29,16 @@ public sealed class SqlServerDialect : ISqlDialect
     /// <inheritdoc/>
     public string LivenessSql => "SELECT 1";
 
+    /// <summary>
+    ///     T-SQL limits after the <c>SELECT</c> keyword, so the whole limit lives in the prefix —
+    ///     <c>"TOP 1 "</c>, trailing space included so <c>SELECT TOP 1 [col]</c> composes with no extra
+    ///     separator at the call site.
+    /// </summary>
+    public string SingleRowLimitPrefix => "TOP 1 ";
+
+    /// <summary>Empty — T-SQL has no trailing row-limit clause (<c>OFFSET/FETCH</c> is a paging construct, not this).</summary>
+    public string SingleRowLimitSuffix => string.Empty;
+
     /// <inheritdoc/>
     public string ListSchemasSql =>
         "SELECT DISTINCT TABLE_SCHEMA FROM INFORMATION_SCHEMA.TABLES ORDER BY TABLE_SCHEMA";