feat: enhance redis and production IA

backend/internal/model/model.go

@@ -19,7 +19,7 @@ type User struct {
 	AuthSource     string         `gorm:"size:20;default:'local'" json:"auth_source"` // local / ldap
 	Role           string         `gorm:"size:20;not null" json:"role"` // admin, dba, developer, auditor
 	IsActive       *bool          `gorm:"default:true" json:"is_active"`
-	Preferences    *string        `gorm:"type:text" json:"preferences"` // JSON: {"theme":"dark","login_style":"split"}
+	Preferences    *string        `gorm:"type:text" json:"preferences"` // JSON: {"theme":"system","login_style":"split"}
 	LastLogin          *time.Time     `json:"last_login"`
 	FailedLoginAttempts int           `gorm:"default:0" json:"failed_login_attempts"`
 	LockedUntil         *time.Time    `json:"locked_until"`