Added Brazillian Portuguese translation on server.json

[Nertonm]

This pull request adds a new Portuguese (Brazil) translation file for the server. The translations/pt_br/server.json file includes translations for various sections such as keyboard actions, login, setup, weekdays, months, and other UI elements.

Key changes include:

• Added translations for keyboard actions, including actions for navigating and manipulating notes, tabs, windows, dialogs, and text note operations.
• Added translations for the login and password setup process, including prompts for entering and confirming passwords.
• Added translations for the setup process, including instructions for syncing with desktop and server instances.
• Added translations for weekdays and months, which are essential for date-related functionalities.
• Added translations for miscellaneous UI elements such as error messages, note sharing, and code block themes.

[eliandoran]

Seems fine, thank you for the contribution.
If you could help with the client translation as well (in src/public/translations), I would appreciate it.