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>

lib/Repository/Support/RepositoryArrayHelper.php

@@ -70,4 +70,27 @@ final class RepositoryArrayHelper
 
         return array_values(array_filter($ids, static fn (int $id): bool => $id > 0));
     }
+
+    /**
+     * Flatten a MintyPHP DB row that can contain nested table-key arrays.
+     *
+     * @return array<string, mixed>
+     */
+    public static function flattenRow(mixed $row): array
+    {
+        if (!is_array($row)) {
+            return [];
+        }
+
+        $flat = [];
+        foreach ($row as $key => $value) {
+            if (is_array($value)) {
+                $flat = array_merge($flat, $value);
+            } elseif (is_string($key)) {
+                $flat[$key] = $value;
+            }
+        }
+
+        return $flat;
+    }
 }