fix(flow): harden proxy phone and checkout recovery paths

tests/address-sources.test.js

@@ -11,6 +11,8 @@ test('address sources normalize supported countries and return local seeds', ()
   assert.equal(api.normalizeCountryCode('澳大利亚'), 'AU');
   assert.equal(api.normalizeCountryCode('印尼'), 'ID');
   assert.equal(api.normalizeCountryCode('日本'), 'JP');
+  assert.equal(api.normalizeCountryCode('韩国'), 'KR');
+  assert.equal(api.normalizeCountryCode('South Korea'), 'KR');
   assert.equal(api.normalizeCountryCode('unknown'), '');
 
   const deSeed = api.getAddressSeedForCountry('DE');
@@ -30,4 +32,9 @@ test('address sources normalize supported countries and return local seeds', ()
   const jpSeed = api.getAddressSeedForCountry('日本');
   assert.equal(jpSeed.countryCode, 'JP');
   assert.equal(jpSeed.fallback.region, 'Tokyo');
+
+  const krSeed = api.getAddressSeedForCountry('Korea');
+  assert.equal(krSeed.countryCode, 'KR');
+  assert.equal(krSeed.fallback.region, 'Seoul');
+  assert.match(krSeed.fallback.postalCode, /^\d{5}$/);
 });