feat(notice): 通知三表与 SystemAdmin email 字段 Scheme 及迁移

database/migrations/20261012000002_system_admin_email.php

@@ -0,0 +1,20 @@
+<?php
+
+use think\migration\Migrator;
+use think\migration\db\Column;
+
+/**
+ * system_admin 追加电子邮箱字段（幂等，已存在则跳过）.
+ */
+class SystemAdminEmail extends Migrator
+{
+    public function change()
+    {
+        $table = $this->table('system_admin');
+
+        if(!$table->hasColumn('email')){
+            $table->addColumn(Column::char('email', 100)->setDefault('')->setComment('电子邮箱'));
+            $table->update();
+        }
+    }
+}