Rename `ko.po` back to `ko_KR.po` (#11074)

While it was renamed from `ko_KR.UTF-8.po` to `ko.po` in #10976,
@uhojin, a Korean locale maintainer, [notes] that “ko_KR [*South*
Korean] makes more sense in locale context just to avoid any potential
confusion between 한국어 vs 조선어”.

Despite `ko_KP` (North Korean) not being present in glibc (as of version
2.43), and the ISO639 maintainers [expressing disapproval of `ko_KP`],
it is possible opinions may change in the future, and individual
opinions may be contested—disambiguating doesn't hurt.

Requesting a review from all involved parties; I wish you ***all* opine
before merging**.

[notes]:
https://github.com/ghostty-org/ghostty/pull/10976#discussion_r2861424171
[expressing disapproval of `ko_KP`]:
https://github.com/ghostty-org/ghostty/pull/10976#discussion_r2861359240

CODEOWNERS

@@ -177,7 +177,7 @@
 /po/id.po @ghostty-org/id_ID
 /po/it.po @ghostty-org/it_IT
 /po/ja.po @ghostty-org/ja_JP
-/po/ko.po @ghostty-org/ko_KR
+/po/ko_KR.po @ghostty-org/ko_KR
 /po/lt.po @ghostty-org/lt_LT
 /po/lv.po @ghostty-org/lv_LV
 /po/mk.po @ghostty-org/mk_MK

src/os/i18n_locales.zig

@@ -37,7 +37,7 @@ pub const locales = [_][:0]const u8{
     "ru",
     "uk",
     "pl",
-    "ko",
+    "ko_KR",
     "mk",
     "tr",
     "id",