fix: secure adult visibility and telegram bot access

internal/model/telegram_binding.go

@@ -0,0 +1,12 @@
+package model
+
+// TelegramBinding links a Telegram account to a local MediaStationGo user.
+// The binding is password-verified when /start is used, then reused for
+// low-risk self-service actions such as toggling adult-library visibility.
+type TelegramBinding struct {
+	Base
+	TelegramUserID int64  `gorm:"uniqueIndex;not null" json:"telegram_user_id"`
+	TelegramName   string `gorm:"size:128" json:"telegram_name,omitempty"`
+	ChatID         int64  `gorm:"index" json:"chat_id"`
+	UserID         string `gorm:"index;size:36;not null" json:"user_id"`
+}