updated the project README to reflect the actual implementation of th…

[fastrack0926]

This PR updates the project README to reflect the actual implementation of the app instead of the earlier aspirational/product-marketing version. It aligns the documentation with the codebase’s current architecture, including Privy authentication, GitHub integration, Prisma-backed data models, and the bounty marketplace workflow.

What this change includes
corrected the auth stack to match the real implementation
clarified the app’s purpose as a GitHub bounty marketplace MVP
added a more accurate project structure overview
documented the current environment variables and setup flow
described the key workflow, architecture, and current roadmap more honestly
improved developer usability by making the README read like a real project guide rather than a pitch document

Why this matters
The previous README described a broader vision and outdated setup steps that did not match the code in the repository. This update reduces confusion for contributors and makes it easier for new developers to understand how the system works and how to run it locally.

Result
The documentation is now better aligned with the codebase and more useful for onboarding, setup, and contribution.

[vercel]

@fastrack0926 is attempting to deploy a commit to the Andrei's projects Team on Vercel.

A member of the Team first needs to authorize it.