fix: support bilingual Booking Excel headers

tests/test_arr_web.py

@@ -3,6 +3,7 @@ from __future__ import annotations
 import base64
 import hashlib
 import json
+import re
 import tempfile
 import unittest
 from datetime import date
@@ -1077,5 +1078,26 @@ class ControlledDownloadTests(unittest.TestCase):
                 reader.read(bad)
 
 
+class BookingHeaderI18nContractTests(unittest.TestCase):
+    def test_booking_header_errors_have_three_locale_messages(self) -> None:
+        script = (STATIC_ROOT / "i18n.js").read_text(encoding="utf-8")
+        expected = {
+            "BOOKING_EXCEL_HEADERS_MISSING": "error.booking_headers_missing",
+            "BOOKING_EXCEL_HEADERS_AMBIGUOUS": "error.booking_headers_ambiguous",
+        }
+        for code, key in expected.items():
+            self.assertIn(f'{code}: "{key}"', script)
+            match = re.search(
+                rf'^\s*"{re.escape(key)}": (\[.*\]),$',
+                script,
+                re.MULTILINE,
+            )
+            self.assertIsNotNone(match, key)
+            values = json.loads(match.group(1))
+            self.assertEqual(len(values), 3, key)
+            self.assertTrue(all(values), key)
+            self.assertRegex(values[2], r"[\u0e00-\u0e7f]", key)
+
+
 if __name__ == "__main__":
     unittest.main()