Fixed flag not displaying for West Virginia (#319)

The flag for West Virginia was not displaying correctly.
This was due to a mismatch between the key (West_Virginia) and the
displayed name (West Virginia).
I corrected the key reference to ensure the flag loads properly.
<img width="171" alt="スクリーンショット 2025-03-23 23 02 02"
src="https://github.com/user-attachments/assets/be18538b-18e5-462c-b52e-b37d6399ae08"
/>

src/client/data/countries.json

@@ -1581,7 +1581,7 @@
     "name": "Washington"
   },
   {
-    "code": "West Virginia",
+    "code": "West_Virginia",
     "name": "West Virginia"
   },
   {