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.

tests/Feature/Integration/TenantIntegrationControllerTest.php

@@ -31,7 +31,7 @@ class TenantIntegrationControllerTest extends TestCase
                     Mockery::on(fn (Integration $argument) => $argument->is($integration)),
                     ['api_key' => 'secret']
                 )
-                ->andReturn(new TenantIntegration());
+                ->andReturn(new TenantIntegration);
         });
 
         $this->postJson('/api/test-tenant/integrations/test_integration', [
@@ -40,7 +40,8 @@ class TenantIntegrationControllerTest extends TestCase
             ],
         ])->assertOk()
             ->assertExactJson([
-                'message' => 'integration configured correctly',
+                'code' => 'integration.configured',
+                'message' => 'Integración configurada correctamente.',
             ]);
     }
 }