ConnectionManagerTest の reference closure を MutableClock に置換

probeReplicas の TTL リフレッシュテストで `use (&$now)` を使用しており、
SlevomatCodingStandard.PHP.DisallowReference (CLAUDE.md 「参照渡し禁止」) に
違反していた。既存の MutableClock helper に置き換えて解消する。

ed023d7 の push 後、CI Code Style ジョブで検出。原因はローカル phpcs 確認時に
出力を切り詰めて exit code を見落とし、エラーを誤って green と報告したこと。
今回は exit code を明示確認した。

Author: logicraft

tests/Unit/Database/ConnectionManagerTest.php

@@ -13,6 +13,7 @@
 use Sloop\Database\Exception\InvalidConfigException;
 use Sloop\Database\Factory\ConnectionFactory;
 use Sloop\Database\Replica\InMemoryDeadReplicaCache;
+use Sloop\Tests\Support\MutableClock;
 use Sloop\Tests\Unit\Database\Stub\AlwaysFailConnectionFactory;
 use Sloop\Tests\Unit\Database\Stub\FixedReplicaSelector;
 use Sloop\Tests\Unit\Database\Stub\ScriptedConnectionFactory;
@@ -954,17 +955,14 @@ public function testProbeReplicasRefreshesDeadMarkTtlOnRepeatedFailure(): void
     {
         // Use a controllable clock so the assertion proves the dead mark was
         // re-stamped by the probe rather than just lingering from the pre-mark.
-        $now   = 1000;
-        $clock = function () use (&$now): int {
-            return $now;
-        };
-        $deadCache = new InMemoryDeadReplicaCache($clock);
+        $clock     = new MutableClock(1000);
+        $deadCache = new InMemoryDeadReplicaCache($clock(...));
 
         // Pre-mark with a short TTL that would naturally expire at 1010.
         $deadCache->markServerDead('replica.internal', 0, 10);
 
         // Advance past the original expiry; sanity-check the pre-mark is gone.
-        $now = 1100;
+        $clock->now = 1100;
         $this->assertFalse($deadCache->isDead('replica.internal', 0, 'master'));
 
         $factory = new ScriptedConnectionFactory();
@@ -996,9 +994,9 @@ public function testProbeReplicasRefreshesDeadMarkTtlOnRepeatedFailure(): void
         // Still dead between the original 1010 expiry and the new 1160 expiry,
         // and gone again past 1160. This proves a fresh stamp, not a stale entry.
         $this->assertTrue($deadCache->isDead('replica.internal', 0, 'master'));
-        $now = 1150;
+        $clock->now = 1150;
         $this->assertTrue($deadCache->isDead('replica.internal', 0, 'master'));
-        $now = 1170;
+        $clock->now = 1170;
         $this->assertFalse($deadCache->isDead('replica.internal', 0, 'master'));
     }