修复(#138): 补齐 errMsg 漏掉的错误码映射

新增 UserCommissionNotEnough、SendSmsError、AreaCodeIsEmpty、
DeviceBindLimitExceeded、ExistAvailableTraffic 五个错误码的中文映射，
修复管理后台审批提现等接口业务校验失败时 msg 被误显为
"Internal Server Error" 的问题。

Co-authored-by: multica-agent <github@multica.ai>

pkg/xerr/errMsg.go

@@ -37,6 +37,7 @@ func init() {
 		TelegramNotBound:              "Telegram not bound ",
 		UserNotBindOauth:              "User not bind oauth method",
 		InviteCodeError:               "Invite code error",
+		UserCommissionNotEnough:       "佣金余额不足",
 		RegisterIPLimit:               "Too many registrations",
 		EmailBindError:                "Email already bound",
 		UserBindInviteCodeExist:       "Invite code already bound",
@@ -82,6 +83,8 @@ func init() {
 		// System error
 		DebugModeError: "Debug mode is enabled",
 
+		SendSmsError: "短信发送失败",
+
 		GetAuthenticatorError:          "Unsupported login method",
 		AuthenticatorNotSupportedError: "The authenticator does not support this method",
 
@@ -94,15 +97,18 @@ func init() {
 		TelephoneExist:                     "Telephone already exists",
 		DeviceExist:                        "device exists",
 		PasswordIsEmpty:                    "password is empty",
+		AreaCodeIsEmpty:                    "国家区号不能为空",
 		TelephoneError:                     "telephone number error",
 		DeviceNotExist:                     "Device does not exist",
 		UseridNotMatch:                     "Userid not match",
+		DeviceBindLimitExceeded:            "设备绑定数量已达上限",
 
 		// Order error
 		OrderNotExist:                 "Order does not exist",
 		PaymentMethodNotFound:         "Payment method not found",
 		OrderStatusError:              "Order status error",
 		InsufficientOfPeriod:          "Insufficient number of period",
+		ExistAvailableTraffic:         "存在可用流量",
 		OrderAlreadyRefunded:          "Order already refunded",
 		OrderRefundNoSubscription:     "Refund target subscription not found",
 		OrderRefundCommissionMismatch: "Refund commission source not found",

pkg/xerr/errMsg_test.go

@@ -0,0 +1,45 @@
+package xerr
+
+import "testing"
+
+// TestMapErrMsg_MissingCodesAreFilled 覆盖 HIF-138 中补齐的 5 个错误码：
+// 这些码之前在 message 表中缺失，导致 MapErrMsg 回退到 "Internal Server Error"。
+func TestMapErrMsg_MissingCodesAreFilled(t *testing.T) {
+	cases := []struct {
+		name string
+		code uint32
+		want string
+	}{
+		{"UserCommissionNotEnough", UserCommissionNotEnough, "佣金余额不足"},
+		{"SendSmsError", SendSmsError, "短信发送失败"},
+		{"AreaCodeIsEmpty", AreaCodeIsEmpty, "国家区号不能为空"},
+		{"DeviceBindLimitExceeded", DeviceBindLimitExceeded, "设备绑定数量已达上限"},
+		{"ExistAvailableTraffic", ExistAvailableTraffic, "存在可用流量"},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			got := MapErrMsg(tc.code)
+			if got == "Internal Server Error" {
+				t.Fatalf("MapErrMsg(%d) fell back to Internal Server Error; expected %q", tc.code, tc.want)
+			}
+			if got != tc.want {
+				t.Errorf("MapErrMsg(%d) = %q, want %q", tc.code, got, tc.want)
+			}
+			if !IsCodeErr(tc.code) {
+				t.Errorf("IsCodeErr(%d) = false, want true", tc.code)
+			}
+		})
+	}
+}
+
+// TestMapErrMsg_UnknownCodeFallsBack 验证未定义码仍然安全回退，不 panic。
+func TestMapErrMsg_UnknownCodeFallsBack(t *testing.T) {
+	const unknown uint32 = 99999
+	if got := MapErrMsg(unknown); got != "Internal Server Error" {
+		t.Errorf("MapErrMsg(%d) = %q, want %q", unknown, got, "Internal Server Error")
+	}
+	if IsCodeErr(unknown) {
+		t.Errorf("IsCodeErr(%d) = true, want false", unknown)
+	}
+}