feat: plugin controller config system with guest_comm_config hook integration

- Add HasPluginConfig trait and PluginController base class
- Integrate guest_comm_config hook in CommController for plugin frontend config injection
- Add user creation functionality to UserService and fix null value handling
- Enhance AbstractPlugin.getConfig() with key parameter support
- Multiple service layer optimizations and architecture improvements

app/Utils/CacheKey.php

@@ -31,7 +31,7 @@ class CacheKey
     /**
      * 生成缓存键
      */
-    public static function get(string $key, $uniqueValue = null): string
+    public static function get(string $key, mixed $uniqueValue = null): string
     {
         // 检查是否为核心键
         if (array_key_exists($key, self::CORE_KEYS)) {