fix: relax NATIONAL_ID regex to accept short codes like DCC (#2167)

* fix: relax NATIONAL_ID external reference regex to accept short codes

The national ID regex required 5-20 characters, rejecting legitimate
short codes like DCC (3 chars), GETW (4 chars), and SEPD (4 chars)
used in the PAYG energy manifest. This caused the nightly Demo Reset
workflow to fail on every run since the PAYG tenant was added.

Lowered the minimum from 5 to 2 characters.

* fix: update boundary tests for relaxed NATIONAL_ID regex

Update minimum length test to use 2-char reference and too-short test
to use 1-char reference, matching the new {2,20} constraint.

---------

Co-authored-by: Ben Coombs <bjcoombs@users.noreply.github.com>

Author: bjcoombs

services/party/domain/party.go

@@ -607,8 +607,8 @@ var (
 	// LEI: 20 alphanumeric characters
 	leiRegex = regexp.MustCompile(`^[A-Z0-9]{20}$`)
 
-	// National ID: varies by country, using a general alphanumeric pattern
-	nationalIDRegex = regexp.MustCompile(`^[A-Z0-9]{5,20}$`)
+	// National ID: varies by country, using a general alphanumeric pattern (min 2 for short codes like DCC)
+	nationalIDRegex = regexp.MustCompile(`^[A-Z0-9]{2,20}$`)
 
 	// Tax ID: varies by country, using a general alphanumeric pattern
 	taxIDRegex = regexp.MustCompile(`^[A-Z0-9]{5,20}$`)

services/party/domain/party_test.go

@@ -357,7 +357,7 @@ func TestParty_SetExternalReference_NationalID(t *testing.T) {
 		},
 		{
 			name:      "minimum length",
-			reference: "AB123",
+			reference: "AB",
 			wantErr:   false,
 		},
 		{
@@ -367,7 +367,7 @@ func TestParty_SetExternalReference_NationalID(t *testing.T) {
 		},
 		{
 			name:      "too short",
-			reference: "AB12",
+			reference: "A",
 			wantErr:   true,
 		},
 		{
@@ -517,6 +517,12 @@ func TestValidateExternalReference(t *testing.T) {
 			refType:   ExternalReferenceTypeNationalID,
 			wantErr:   false,
 		},
+		{
+			name:      "valid short national ID",
+			reference: "DCC",
+			refType:   ExternalReferenceTypeNationalID,
+			wantErr:   false,
+		},
 		{
 			name:      "valid tax ID",
 			reference: "GB123456789",