zh locale: take ui/windows images from Longju

The character window's tabs and stat labels (VIT/INT/Character Status,
Status/Abilities/...) are baked into locale/<xx>/ui/windows/windows.dds;
the zh build only overlaid text keys, so they stayed English. The folder
is now replaced as a whole (its .sub files index its own atlas).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

scripts/test_build_zh_locale.py

@@ -26,6 +26,10 @@ class LocaleBuildTest(unittest.TestCase):
             (zh / "locale_interface.txt").write_bytes("ACCEPT\t确定\n".encode("gbk"))
             (en / "item_proto").write_bytes(b"40250-proto")
             (zh / "item_proto").write_bytes(b"old-proto")
+            for path, atlas in ((en, b"en-atlas"), (zh, b"zh-atlas")):
+                (path / "ui/windows").mkdir(parents=True)
+                (path / "ui/windows/windows.dds").write_bytes(atlas)
+            (zh / "ui/windows/zh_only.sub").write_bytes(b"sub")
             (client / "pack").mkdir()
             (client / "pack/Index").write_bytes(b"PACK\r\nlocale/de/\r\nlocale_de\r\nlocale/en/\r\nlocale_en\r\n")
             (client / "pack/locale_en.eix").write_bytes(b"en")
@@ -41,6 +45,8 @@ class LocaleBuildTest(unittest.TestCase):
             self.assertIn("BAD\t%s at %d\tSA", merged)
             self.assertIn("ONLY_EN\tFallback", merged)
             self.assertEqual((staged / "item_proto").read_bytes(), b"40250-proto")
+            self.assertEqual((staged / "ui/windows/windows.dds").read_bytes(), b"zh-atlas")
+            self.assertFalse((staged / "ui/windows/zh_only.sub").exists())
             self.assertEqual((output / "locale.cfg").read_text(), "10002 936 zh\n")
             self.assertEqual((output / "locale_zh.cfg").read_text(), "10002 936 zh\n")
             # A pack/ of its own: original packs linked, locale_zh packed from the staging dir and registered.