test: 移植 ListingStatsTest（9 tests）

unit bootstrap 改載入真實 TMDO_Listing_Stats：先 define
TMDO_TEST_SKIP_LISTING_STATS_STUB，核心 bootstrap 便會跳過它的 stub。
145 → 154 tests。

tests/bootstrap.php

@@ -13,6 +13,9 @@
 
 declare(strict_types=1);
 
+// Load the real TMDO_Listing_Stats below instead of core's stub.
+define( 'TMDO_TEST_SKIP_LISTING_STATS_STUB', true );
+
 $tmdo_core_bootstrap = dirname( __DIR__, 2 ) . '/2meet-data-optimizer/tests/bootstrap.php';
 if ( ! file_exists( $tmdo_core_bootstrap ) ) {
 	throw new RuntimeException(
@@ -44,9 +47,7 @@ $tmdo_hp_files = array(
 	'includes/class-tmdo-hivepress-transient-filter.php',
 	'includes/class-tmdo-hivepress-term-comment-fields.php',
 	'includes/class-tmdo-hpct-import.php',
-	// class-tmdo-listing-stats.php is deliberately NOT loaded: the core unit
-	// bootstrap already declares a TMDO_Listing_Stats stub, and no test in this
-	// suite exercises the real implementation.
+	'includes/class-tmdo-listing-stats.php',
 	'admin/class-tmdo-admin-hivepress.php',
 	'cli/class-tmdo-cli-hivepress.php',
 );