Upgrade open source PHP website to 8.3 version and refactor it

Description

Upgrade open source PHP website to 8.3 version and refactor the code.
This task may take a long time, such as a month or more. Therefore, to understand what the cost of the entire project will be, please write the cost of your hour of work in $ and whether you are available for full-time permanent employment in this project so as not to be distracted by other projects.
Our project currently runs on PHP 7.4 and uses server-side page rendering in the Yii 2 framework. We are using a dedicated server for the project and want to migrate to the Digital Ocean App Platform.
Tasks:
- Upgrade code from PHP 7.3 to 8.4- Remove server-side page rendering, create an API module and use any popular front-end UI framework (admin panel) to replace all interfaces that are currently used in server-side page rendering.- Improve and refactor the code so that the api and bot modules work correctly after migrating the code from the server to the Digital Ocean App Platform.
https://github.com/opensourcewebsite-org/opensourcewebsite-org
OpenSourceWebsite (OSW) - Creating an Open and Democratic Online Community. We promote a free society where everyone can participate in decision-making through electronic voting and where open source guarantees data security.
Russian-speaking candidates are preferred.