feat(branding): rebrand user-facing GPUStack to MesaStack

Applied via scripts/rebrand across UI labels, page title, and all
locale strings (en/zh/ja/ru/tr). Functional references untouched:
npm package, URLs, paths, JS identifiers, GPUSTACK_ constants, and the
X-GPUStack-Model header. The backend-contract startsWith string in
llmodels/hooks keeps "GPUStack server" to stay matchable. Logo images
intentionally left unchanged for now.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/locales/ja-JP/users.ts

@@ -40,14 +40,14 @@ export default {
   'users.password.confirm.empty': '新しいパスワードを確認してください。',
   'users.password.confirm.error': '入力された2つのパスワードが一致しません。',
   'users.login.title': 'ログイン',
-  'users.version.islatest': 'GPUStack {version} は最新バージョンです',
-  'users.version.update': 'GPUStack {version} が利用可能です',
+  'users.version.islatest': 'MesaStack {version} は最新バージョンです',
+  'users.version.update': 'MesaStack {version} が利用可能です',
   'users.settings.title': 'User Settings',
   'users.status.activate': 'Activate Account',
   'users.status.deactivate': 'Deactivate Account',
   'users.status.inactiveAccount': 'Inactive Account',
   'users.login.getInitialPassword':
-    'Run the following command on your GPUStack Server to retrieve the initial admin password.'
+    'Run the following command on your MesaStack Server to retrieve the initial admin password.'
 };
 
 // ========== To-Do: Translate Keys (Remove After Translation) ==========
@@ -55,5 +55,5 @@ export default {
 // 2. 'users.status.activate': 'Activate Account',
 // 3. 'users.status.deactivate': 'Deactivate Account',
 // 4. 'users.status.inactiveAccount': 'Inactive Account',
-// 5. 'users.login.getInitialPassword': 'Run the following command on your GPUStack Server to retrieve the initial admin password.'
+// 5. 'users.login.getInitialPassword': 'Run the following command on your MesaStack Server to retrieve the initial admin password.'
 // ========== End of To-Do List ==========