feat: trial 赠送改为白名单邮箱域名控制

- 新增 EnableTrialEmailWhitelist + TrialEmailDomainWhitelist 配置
- 邮箱注册/登录：加白名单域名判断，域名匹配才赠送 trial
- 设备登录/手机注册：移除 activeTrial，不再自动赠送
- 绑定邮箱(bindEmailWithVerification)：绑定成功后检查白名单+防重复赠送
- 新增 IsEmailDomainWhitelisted 导出函数供跨包调用
- 清理 deviceLoginLogic/telephoneUserRegisterLogic 中的 activeTrial 死代码

Co-Authored-By: claude-flow <ruv@ruv.net>

internal/config/config.go

@@ -90,7 +90,9 @@ type RegisterConfig struct {
 	IpRegisterLimit         int64  `yaml:"IpRegisterLimit" default:"0"`
 	IpRegisterLimitDuration int64  `yaml:"IpRegisterLimitDuration" default:"0"`
 	EnableIpRegisterLimit   bool   `yaml:"EnableIpRegisterLimit" default:"false"`
-	DeviceLimit             int64  `yaml:"DeviceLimit" default:"2"`
+	DeviceLimit               int64  `yaml:"DeviceLimit" default:"2"`
+	EnableTrialEmailWhitelist bool   `yaml:"EnableTrialEmailWhitelist" default:"false"`
+	TrialEmailDomainWhitelist string `yaml:"TrialEmailDomainWhitelist" default:""`
 }
 
 type EmailConfig struct {