i18n: Add Traditional Chinese (zh-TW) locale

### ❓ 為什麼改 (Why)
- Support Traditional Chinese (zh-TW) language for users in Taiwan and other regions using Traditional Chinese.

### 🛠️ 改了什麼 (What)
- Added `messages.zh-TW.xlf` translation file.
- Registered `zh-TW` in `project.json` angular locales.
- Added `zh-TW` option to user-account-settings component dropdown.

### 🚨 驗證狀態 (Verification)
- [x] Linter 通過
- [x] 本地測試通過

apps/client/project.json

@@ -53,6 +53,10 @@
       "zh": {
         "baseHref": "/zh/",
         "translation": "apps/client/src/locales/messages.zh.xlf"
+      },
+      "zh-TW": {
+        "baseHref": "/zh-TW/",
+        "translation": "apps/client/src/locales/messages.zh-TW.xlf"
       }
     },
     "sourceLocale": "en"
@@ -142,6 +146,10 @@
           "baseHref": "/zh/",
           "localize": ["zh"]
         },
+        "development-zh-TW": {
+          "baseHref": "/zh-TW/",
+          "localize": ["zh-TW"]
+        },
         "production": {
           "budgets": [
             {
@@ -260,6 +268,9 @@
         "development-zh": {
           "buildTarget": "client:build:development-zh"
         },
+        "development-zh-TW": {
+          "buildTarget": "client:build:development-zh-TW"
+        },
         "production": {
           "buildTarget": "client:build:production"
         }
@@ -284,7 +295,8 @@
           "messages.pt.xlf",
           "messages.tr.xlf",
           "messages.uk.xlf",
-          "messages.zh.xlf"
+          "messages.zh.xlf",
+          "messages.zh-TW.xlf"
         ],
         "trim": true
       }

apps/client/src/app/components/user-account-settings/user-account-settings.component.ts

@@ -95,7 +95,8 @@ export class GfUserAccountSettingsComponent implements OnInit {
     'pt',
     'tr',
     'uk',
-    'zh'
+    'zh',
+    'zh-TW'
   ];
   public user: User;