fix: Add Livewire config and custom 404 page for subdirectory support

- Add config/livewire.php with app_url and asset_url settings
- Add custom 404 error page with consistent design
- Add error translations for all 8 languages

For subdirectory deployment:
1. Set APP_URL to include subdirectory (e.g., https://example.com/kb)
2. Set ASSET_URL if using CDN
3. Clear config cache after deployment

src/lang/ko/messages.php

@@ -115,6 +115,14 @@
         'already_registered' => '이미 계정이 있으신가요?',
     ],
 
+    // Errors
+    'errors' => [
+        '404_title' => '페이지를 찾을 수 없습니다',
+        'page_not_found' => '페이지를 찾을 수 없습니다',
+        'page_not_found_description' => '찾고 계신 페이지를 찾을 수 없습니다.',
+        'back_to_home' => '홈으로 돌아가기',
+    ],
+
     // Profile
     'profile' => [
         'title' => '프로필',