Normalize country code to UK instead of GB

- CountriesTool: use 'uk' key for United Kingdom
- EGFRatingsHandler: keep UK as-is (no conversion to GB)
- Pairable: convert GB to UK (inverse of previous behavior)

api-webapp/src/main/kotlin/org/jeudego/pairgoth/model/Pairable.kt

@@ -107,9 +107,9 @@ fun Player.Companion.fromJson(json: Json.Object, default: Player? = null) = Play
     rating = json.getInt("rating") ?: default?.rating ?: badRequest("missing rating"),
     rank = json.getInt("rank") ?: default?.rank ?: badRequest("missing rank"),
     country = ( json.getString("country") ?: default?.country ?: badRequest("missing country") ).let {
-        // EGC uses UK, while FFG and browser language use GB
+        // normalize to UK (EGF uses UK, ISO uses GB)
         val up = it.uppercase(Locale.ROOT)
-        if (up == "UK") "GB" else up
+        if (up == "GB") "UK" else up
     },
     club = json.getString("club") ?: default?.club ?: badRequest("missing club"),
     final = json.getBoolean("final") ?: default?.final ?: true,

view-webapp/src/main/kotlin/org/jeudego/pairgoth/ratings/EGFRatingsHandler.kt

@@ -36,9 +36,6 @@ object EGFRatingsHandler: RatingsHandler(RatingsManager.Ratings.EGF) {
                                 if (adjusted < 0) "${-(adjusted - 99) / 100}k"
                                 else "${(adjusted + 100) / 100}d"
                         }
-                        if ("UK" == player.getString("country")) {
-                            player["country"] = "GB"
-                        }
                         // fix for missing firstnames
                         if (player.getString("firstname") == null) {
                             player["firstname"] = ""

view-webapp/src/main/kotlin/org/jeudego/pairgoth/view/CountriesTool.kt

@@ -95,7 +95,7 @@ class CountriesTool {
             "fj" to "Fiji",
             "fr" to "France",
             "ga" to "Gabon",
-            "gb" to "United Kingdom",
+            "uk" to "United Kingdom",
             "gd" to "Grenada",
             "ge" to "Georgia",
             "gg" to "Guernsey",