feat: integrate Cloudflare Turnstile for enhanced security in sign-up and email verification processes. Implement rate limiting for sign-up attempts and add Turnstile validation to prevent abuse. Update environment configuration to support Turnstile keys and enhance user experience with improved error handling and feedback.

feat: implement admin panel with multiple routes for user management, credits, jobs, and content moderation. Add admin dashboard for platform overview and integrate visibility controls for featured content. Enhance sidebar navigation for admin access and ensure proper session handling for admin users.

feat: enhance testing capabilities and introduce new components for question management. Add testing section in AGENTS.md with instructions for running tests and configuring the test environment. Update package.json files to include test scripts and integrate @electric-sql/pglite for in-memory database testing. Introduce CalloutCard and update FilterBar and SoalBrowser components to support visibility filters for private and public questions. Implement new test cases for various functionalities across the application.