chore(l10n): unmap dropped locales from Crowdin, add uk to setup picker

Follow-up to the arb removal: unmap ar/hi/ko/nl/zh-CN/zh-TW in
crowdin.yml so crowdin pull does not recreate them, trim the dead
entries from both language pickers, and add the missing uk entry to
the setup-screen picker.

crowdin.yml

@@ -6,18 +6,15 @@ files:
         # Keys MUST be the project's Crowdin language ids; values are the
         # %locale% suffix used in app_%locale%.arb (underscores so Flutter
         # gen-l10n parses them — hyphenated filenames break gen-l10n).
-        ar: ar
+        # Locales below the 70% translation threshold (ar, hi, ko, nl,
+        # zh-CN, zh-TW) are unmapped so `crowdin pull` doesn't recreate
+        # their arb files; re-add a mapping line when one qualifies.
         de: de
         es-ES: es_ES
         fr: fr
-        hi: hi
         id: id
         ja: ja
-        ko: ko
-        nl: nl
         pt-PT: pt_PT
         ru: ru
         tr: tr
         uk: uk
-        zh-CN: zh_CN
-        zh-TW: zh_TW

lib/screens/settings/appearance_settings_page.dart

@@ -693,18 +693,12 @@ class _LanguageSelector extends StatelessWidget {
     ('es', 'Español', Icons.language),
     ('es_ES', 'Español (España)', Icons.language),
     ('fr', 'Français', Icons.language),
-    ('hi', 'हिन्दी', Icons.language),
     ('ja', '日本語', Icons.language),
-    ('ko', '한국어', Icons.language),
-    ('nl', 'Nederlands', Icons.language),
     ('pt', 'Português', Icons.language),
     ('pt_PT', 'Português (Brasil)', Icons.language),
     ('ru', 'Русский', Icons.language),
     ('tr', 'Türkçe', Icons.language),
     ('uk', 'Українська', Icons.language),
-    ('zh', '简体中文', Icons.language),
-    ('zh_CN', '简体中文 (中国)', Icons.language),
-    ('zh_TW', '繁體中文', Icons.language),
   ];
 
   /// Uses filteredLocaleCodes from supported_locales.dart (generated file).

lib/screens/setup_screen.dart

@@ -709,17 +709,12 @@ class _SetupScreenState extends ConsumerState<SetupScreen> {
     ('es', 'Español', Icons.language),
     ('es_ES', 'Español (España)', Icons.language),
     ('fr', 'Français', Icons.language),
-    ('hi', 'हिन्दी', Icons.language),
     ('ja', '日本語', Icons.language),
-    ('ko', '한국어', Icons.language),
-    ('nl', 'Nederlands', Icons.language),
     ('pt', 'Português', Icons.language),
     ('pt_PT', 'Português (Brasil)', Icons.language),
     ('ru', 'Русский', Icons.language),
     ('tr', 'Türkçe', Icons.language),
-    ('zh', '简体中文', Icons.language),
-    ('zh_CN', '简体中文 (中国)', Icons.language),
-    ('zh_TW', '繁體中文', Icons.language),
+    ('uk', 'Українська', Icons.language),
   ];
 
   List<(String, String, IconData)> get _filteredLanguages {