Add ISO 3166-1 user-assigned code elements

ISO 3166-1 reserves certain alpha-2 codes for user assignment:
- AA
- QM to QZ
- XA to XZ
- ZZ

These codes are part of the ISO 3166-1 standard and are reserved for
users who need to add further code elements for their own purposes.
They will never be assigned to actual country names by ISO.

Common uses include:
- XX: Unknown or Unspecified Country
- XY: Anonymous Country (for privacy)
- XK: Kosovo (used by European Commission)
- ZZ: Unknown or International

Reference: https://en.wikipedia.org/wiki/ISO_3166-1_alpha-2#User-assigned_code_elements

Author: claude

server/tx/tx_countrycode.pas

@@ -440,6 +440,52 @@ procedure TCountryCodeServices.load;
   doLoad('ZM', 'Zambia');
   doLoad('ZW', 'Zimbabwe');
 
+  // ISO 3166-1 User-assigned code elements
+  // These codes are reserved for user assignment and will never be used for country names
+  // See: https://en.wikipedia.org/wiki/ISO_3166-1_alpha-2#User-assigned_code_elements
+  doLoad('AA', 'User-assigned');
+  doLoad('QM', 'User-assigned');
+  doLoad('QN', 'User-assigned');
+  doLoad('QO', 'User-assigned');
+  doLoad('QP', 'User-assigned');
+  doLoad('QQ', 'User-assigned');
+  doLoad('QR', 'User-assigned');
+  doLoad('QS', 'User-assigned');
+  doLoad('QT', 'User-assigned');
+  doLoad('QU', 'User-assigned');
+  doLoad('QV', 'User-assigned');
+  doLoad('QW', 'User-assigned');
+  doLoad('QX', 'User-assigned');
+  doLoad('QY', 'User-assigned');
+  doLoad('QZ', 'User-assigned');
+  doLoad('XA', 'User-assigned');
+  doLoad('XB', 'User-assigned');
+  doLoad('XC', 'User-assigned');
+  doLoad('XD', 'User-assigned');
+  doLoad('XE', 'User-assigned');
+  doLoad('XF', 'User-assigned');
+  doLoad('XG', 'User-assigned');
+  doLoad('XH', 'User-assigned');
+  doLoad('XI', 'User-assigned');
+  doLoad('XJ', 'User-assigned');
+  doLoad('XK', 'User-assigned');  // Note: XK is also used for Kosovo by the European Commission
+  doLoad('XL', 'User-assigned');
+  doLoad('XM', 'User-assigned');
+  doLoad('XN', 'User-assigned');
+  doLoad('XO', 'User-assigned');
+  doLoad('XP', 'User-assigned');
+  doLoad('XQ', 'User-assigned');
+  doLoad('XR', 'User-assigned');
+  doLoad('XS', 'User-assigned');
+  doLoad('XT', 'User-assigned');
+  doLoad('XU', 'User-assigned');
+  doLoad('XV', 'User-assigned');
+  doLoad('XW', 'User-assigned');
+  doLoad('XX', 'User-assigned');  // Commonly used for "Unknown" or "Unspecified"
+  doLoad('XY', 'User-assigned');  // Commonly used for "Anonymous" (privacy)
+  doLoad('XZ', 'User-assigned');
+  doLoad('ZZ', 'User-assigned');  // Commonly used for "Unknown" or "International"
+
   doLoad('ABW', 'Aruba');
   doLoad('AFG', 'Afghanistan');
   doLoad('AGO', 'Angola');