Refactor: File-scoped namespaces, remove unused usings, and implement primary constructors

[samanazadi1996]

This pull request focuses on improving code quality and maintainability by:

• Converting all namespaces to file-scoped, reducing clutter and enhancing readability.
• Removing unused using directives to clean up the code and eliminate unnecessary dependencies.
• Applying primary constructors for more concise and efficient object initialization.
• Correcting minor typos found across the codebase.

These changes streamline the project structure without introducing any breaking changes or altering functionality, making the codebase easier to navigate and maintain.

[samanazadi1996]

Hello @joseharriaga ,

I recently submitted this pull request that contains a large number of changes (around 830 files) to convert namespaces to file-scoped namespaces. I believe these changes are valuable and help improve the structure of the code.

Given that the project is under continuous development, there is a high risk of conflicts if this PR is not reviewed soon. Since these changes do not affect the core logic, I would appreciate it if you could review the PR at your earliest convenience.

If there are any issues or concerns with the changes, I’m happy to address them promptly.