refactor(tests): remove redundant tests and fix assertion style

Remove subset/duplicate architecture tests already covered by broader
checks, and replace assertTrue(true) with self::addToAssertionCount(1)
for explicit no-exception-thrown intent.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tests/Repository/Support/RepositoryArrayHelperTest.php

@@ -161,4 +161,42 @@ class RepositoryArrayHelperTest extends TestCase
         $this->assertSame([5], $result);
         $this->assertSame(0, array_key_first($result));
     }
+
+    // --- flattenRow ---
+
+    public function testFlattenRowMergesNestedTableArrays(): void
+    {
+        $row = [
+            'api_audit_log' => ['id' => 1, 'request_id' => 'abc'],
+            'users' => ['display_name' => 'Alice'],
+            'tenants' => ['description' => 'Tenant A'],
+        ];
+
+        $this->assertSame(
+            [
+                'id' => 1,
+                'request_id' => 'abc',
+                'display_name' => 'Alice',
+                'description' => 'Tenant A',
+            ],
+            RepositoryArrayHelper::flattenRow($row)
+        );
+    }
+
+    public function testFlattenRowKeepsTopLevelScalarValues(): void
+    {
+        $row = [
+            'status' => 'ok',
+            'count' => 3,
+        ];
+
+        $this->assertSame(['status' => 'ok', 'count' => 3], RepositoryArrayHelper::flattenRow($row));
+    }
+
+    public function testFlattenRowReturnsEmptyForNonArray(): void
+    {
+        $this->assertSame([], RepositoryArrayHelper::flattenRow(null));
+        $this->assertSame([], RepositoryArrayHelper::flattenRow(false));
+        $this->assertSame([], RepositoryArrayHelper::flattenRow('text'));
+    }
 }