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

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

tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Sql.Tests/SqlServerDialectTests.cs

@@ -48,6 +48,19 @@ public class SqlServerDialectTests
         d.ListColumnsSql.ShouldContain("@table");
     }
 
+    [Fact]
+    public void SingleRowLimit_isTSqlsTop1_inThePrefixPosition_withItsOwnTrailingSpace()
+    {
+        var d = new SqlServerDialect();
+
+        // The planner concatenates "SELECT " + prefix + columns with no separator of its own, so the
+        // trailing space belongs to the fragment. T-SQL has no end-of-statement limit clause.
+        d.SingleRowLimitPrefix.ShouldBe("TOP 1 ");
+        d.SingleRowLimitSuffix.ShouldBe("");
+        string.Concat("SELECT ", d.SingleRowLimitPrefix, "[a]", d.SingleRowLimitSuffix)
+            .ShouldBe("SELECT TOP 1 [a]");
+    }
+
     // ---- extra guards on the injection boundary (beyond the plan's golden set) ----
 
     [Fact]