refactor: flatten src/AKSRT → src (drop theme-identifier dir)

Move all domain folders from src/AKSRT/{Domain} to src/{Domain}; remap
Composer PSR-4 "AKSRT\\": "src/"; update audit script + README + ADR
paths; remove dead tools/build-psr4-map.php (scanned deleted inc/classes).

src/Admin/Schema/SchemaTools.php

@@ -0,0 +1,24 @@
+<?php
+/**
+ * @package AKSRT
+ */
+
+namespace AKSRT\Admin\Schema;
+
+defined('ABSPATH') || exit;
+
+class SchemaTools {
+
+    public static function build(): array {
+        return [
+            'domain'   => 'tools',
+            'title'    => '工具&诊断',
+            'sections' => [
+                'import-export'  => SchemaToolsImportExport::build(),
+                'health'         => SchemaToolsHealth::build(),
+                'backup'         => SchemaToolsBackup::build(),
+                'email-rollback' => SchemaToolsEmailRollback::build(),
+            ],
+        ];
+    }
+}