Remove duplicate bottom border when displaying headers only

- Fix duplicate border issue when displaying table with headers but no rows
- Update test to reflect correct behavior (single border after headers)
- Improves visual consistency for incremental row display
- All tests pass

Co-authored-by: swissspidy <841956+swissspidy@users.noreply.github.com>

Author: Copilot

lib/cli/Table.php

@@ -195,7 +195,8 @@ public function getDisplayLines() {
 			$out = array_merge( $out, $row );
 		}
 
-		if (isset($border)) {
+		// Only add final border if there are rows
+		if (!empty($this->_rows) && isset($border)) {
 			$out[] = $border;
 		}
 

tests/Test_Table_Ascii.php

@@ -249,7 +249,6 @@ public function testDrawWithHeadersNoData() {
 +----------+----------+
 | header 1 | header 2 |
 +----------+----------+
-+----------+----------+
 
 OUT;
 		$this->assertInOutEquals(array($headers, $rows), $output);