Add Development CI Pipeline with Linting and Automated Testing

[mimi030]

This pull request introduces a CI pipeline for the dev branch, aimed at enhancing code quality and ensuring reliable functionality through automated checks. The following key components are included:

- Backend Linting with Flake8:

• Ensures Python code follows style guidelines and best practices.

- Frontend Linting with ESLint:

• Checks JavaScript/TypeScript code for syntax errors, style issues, and potential bugs.

- Automated Testing:

• Backend: Runs Django test suite to validate backend functionality.
• Frontend: Executes Playwright tests in parallel across multiple shards to verify frontend UI behavior and responsiveness.

- Artifact Generation:

• Uploads test reports as artifacts for easy inspection.

[mimi030]

Review completed, ready for the next steps.