fix(radio): resolve common country exonyms Intl.DisplayNames omits (#232)

Recognize common country names and exonyms in Radio country requests and station filtering. Keep ambiguous country names rejected.

src/data/radioCountry.test.mjs

@@ -18,6 +18,37 @@ test('Radio country normalization maps ISO codes and bounded common names', () =
   }
 });
 
+test('Radio country normalization resolves common English names/exonyms ICU misses', () => {
+  // Each of these fails closed against the Intl.DisplayNames primary label
+  // alone (e.g. TR is "Türkiye", MM is "Myanmar (Burma)", AE is "United Arab
+  // Emirates"), so a request like "play radio in Turkey" would return nothing.
+  for (const [input, code] of [
+    ['Turkey', 'TR'],
+    ['Turkiye', 'TR'],
+    ['Myanmar', 'MM'],
+    ['Burma', 'MM'],
+    ['UAE', 'AE'],
+    ['U.A.E.', 'AE'],
+    ['Holland', 'NL'],
+    ['Swaziland', 'SZ'],
+    ['East Timor', 'TL'],
+    ['Cabo Verde', 'CV'],
+    ['Vatican', 'VA'],
+  ]) {
+    const result = normalizeRadioCountryInput(input);
+    assert.equal(result.valid, true, input);
+    assert.equal(result.code, code, input);
+  }
+});
+
+test('Ambiguous country names still fail closed (no broadened selection)', () => {
+  // Two states share the name "Congo" (CD/CG), so a bare mention must not
+  // resolve to either — it stays low-confidence and fails closed.
+  for (const input of ['Congo', 'Korea']) {
+    assert.equal(normalizeRadioCountryInput(input).valid, false, input);
+  }
+});
+
 test('Radio country normalization rejects malformed, non-ISO, and oversized values', () => {
   for (const input of [
     'ZZ',