feat: 添加联系我们配置接口和字典配置缓存

1. 新增DictionaryItem字典配置结构体
2. 添加字典配置缓存及失效逻辑
3. 实现联系我们接口的业务逻辑和测试用例
4. 注册联系我们API路由
5. 集成字典配置到admin内部客户端
6. 处理字典配置更新的kafka事件

server/admin_internal_config.go

@@ -168,6 +168,19 @@ func (c *adminInternalClient) ThirdPartyConfig(group string, keys ...string) (ma
 	return wrapper.Values, nil
 }
 
+func (c *adminInternalClient) DictionaryConfig(dictType string) ([]types.DictionaryItem, error) {
+	var wrapper struct {
+		Items []types.DictionaryItem `json:"items"`
+	}
+	if err := c.getJSON("/internal/im-config/dictionary/"+url.PathEscape(strings.TrimSpace(dictType)), nil, &wrapper); err != nil {
+		return nil, err
+	}
+	if wrapper.Items == nil {
+		wrapper.Items = []types.DictionaryItem{}
+	}
+	return wrapper.Items, nil
+}
+
 func (c *adminInternalClient) ModerationProvider() (*types.ModerationProviderConfig, error) {
 	var result types.ModerationProviderConfig
 	if err := c.getJSON("/internal/im-config/moderation/provider", nil, &result); err != nil {