Add Global vendor country region

Allow vendor country selections to use a Global region alongside
existing country and EU values. The new value is accepted by backend
country-code validation, exposed through GraphQL and MCP schemas, and
shown in the shared country picker label set.

Signed-off-by: Cursor Agent <cursoragent@cursor.com>

Co-authored-by: Bryan FRIMIN <bryan@frimin.fr>

pkg/coredata/country_code.go

@@ -25,6 +25,10 @@ type (
 	CountryCode string
 )
 
+const (
+	CountryCodeGlobal CountryCode = "GLOBAL"
+)
+
 const (
 	CountryCodeAD CountryCode = "AD"
 	CountryCodeAE CountryCode = "AE"
@@ -286,6 +290,7 @@ var (
 func (v CountryCode) IsValid() bool {
 	switch v {
 	case
+		CountryCodeGlobal,
 		CountryCodeAD,
 		CountryCodeAE,
 		CountryCodeAF,

pkg/coredata/migrations/20260528T182700Z.sql

@@ -0,0 +1,16 @@
+-- Copyright (c) 2026 Probo Inc <hello@getprobo.com>.
+--
+-- Permission to use, copy, modify, and/or distribute this software for any
+-- purpose with or without fee is hereby granted, provided that the above
+-- copyright notice and this permission notice appear in all copies.
+--
+-- THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+-- REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+-- AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+-- INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+-- LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+-- OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+-- PERFORMANCE OF THIS SOFTWARE.
+
+-- Add the Global region to vendor country selections.
+ALTER TYPE country_code ADD VALUE 'GLOBAL' BEFORE 'AD';