Fix: content screen home and excel export

[Savecoders]

This pull request introduces several updates to the project, including a rebranding effort, improved UI elements, and enhancements to the Excel export functionality. The most significant changes involve renaming the application, adding new features for file handling, and refining the user interface for better usability.

Rebranding and Naming Updates:

• Renamed the application from "Light Vitae" to "SIMEVEC" across multiple files, including README.md, lib/app.dart, lib/utils/events/splash_screen.dart, and various UI components. This includes updates to titles, footers, and other branding elements. [1] [2] [3] [4] [5] [6] [7]

Excel Export Enhancements:

• Removed the Firestore-specific export functionality and replaced it with a generalized saveFileToDownloads method to save files locally on non-web platforms. Added platform-specific handling for file storage and opening. [1] [2]

UI and Navigation Improvements:

• Updated the login and selection screens with enhanced visuals, including background images, shadows, and text alignment. Added a back button to the "Login Empleado" screen for improved navigation. [1] [2] [3]
• Adjusted layout structures in the home view by replacing Expanded with Column for better flexibility.

Code Cleanup and Refactoring:

• Removed unused imports and commented-out code across multiple files, including lib/routes.dart and lib/services/service_locator.dart. [1] [2] [3]

Employee Attendance Improvements:

• Enhanced the _fetchAsistencias method in lib/view/reports/empleado.dart to include robust validation for employee data and improved filtering logic for Firestore queries.