Implement localization for API responses and error messages

- Added localization support for API responses in English and Spanish.
- Introduced a middleware to set the API locale based on the Accept-Language header.
- Updated various exception messages and validation responses to use localized strings.
- Created new language files for English and Spanish translations.
- Refactored existing code to replace hardcoded messages with localized strings.
- Added tests to verify localization functionality and response correctness.

config/app.php

@@ -78,9 +78,11 @@ return [
     |
     */
 
-    'locale' => env('APP_LOCALE', 'en'),
+    'locale' => env('APP_LOCALE', 'es'),
 
-    'fallback_locale' => env('APP_FALLBACK_LOCALE', 'en'),
+    'fallback_locale' => env('APP_FALLBACK_LOCALE', 'es'),
+
+    'supported_locales' => ['es', 'en'],
 
     'faker_locale' => env('APP_FAKER_LOCALE', 'en_US'),