This pull request adds support for Spanish (es-ES) localization throughout the backend and frontend of the application. The changes include updating data models, validation, language bundles, and frontend language selection, as well as adding a comprehensive Spanish translation file and improving the Spanish README documentation.

Backend internationalization and validation updates:

• Added Es field to the Locale struct in agent/app/dto/app.go to support Spanish localization.
• Updated the Login struct in core/app/dto/auth.go to include 'es-ES' in the allowed language options for validation.
• Registered the Spanish language bundle in both agent/i18n/i18n.go and core/i18n/i18n.go by loading lang/es-ES.yaml. [1] [2]
• Added a new Spanish translation file core/i18n/lang/es-ES.yaml containing all necessary keys for backend error messages, commands, and system notifications.

Frontend internationalization enhancements:

• Imported Spanish locale from Element Plus and updated language selection logic in frontend/src/App.vue to support es-es. [1] [2]
• Updated the App.Language type in frontend/src/api/interface/app.ts to include 'es-es'.
• Registered Spanish translations in the frontend language module and made them available under the 'es-ES' key in frontend/src/lang/index.ts. [1] [2]

Documentation improvements:

• Renamed the Spanish README file to README.es-es.md and improved translation quality and terminology for clarity and consistency. [1] [2]Created Spanish files es-ES Spain

First try