move Language Selector into SettingDialog (#352)

* fix:custom model setting bug

* refactor: consolidate aiProvider checks for cleaner code

* fix:Integrated the language selection option into the `SettingsDialog`

* fix:useSearchParams() should be wrapped in a suspense boundary at page

* fix: improve semantic HTML and maintainability

- Replace nested button>a with proper anchor element for GitHub link
- Use i18n.locales.map() with LANGUAGE_LABELS for language options

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Co-authored-by: dayuan.jiang <jdy.toh@gmail.com>

lib/i18n/dictionaries/ja.json

@@ -14,6 +14,7 @@
         "about": "概要",
         "editor": "エディタ",
         "newChat": "新しいチャットを開始",
+        "github": "GitHub",
         "settings": "設定",
         "hidePanel": "チャットパネルを非表示 (Ctrl+B)",
         "showPanel": "チャットパネルを表示 (Ctrl+B)",
@@ -87,6 +88,8 @@
         "overrides": "上書き",
         "clearSettings": "設定をクリア",
         "useServerDefault": "サーバーデフォルトを使用",
+        "language": "言語",
+        "languageDescription": "インターフェース言語を選択します。",
         "theme": "テーマ",
         "themeDescription": "インターフェースと DrawIO キャンバスのダーク/ライトモード。",
         "drawioStyle": "DrawIO スタイル",