Add Multiple Authentication Providers (GitHub & Facebook) Alongside Google Auth

[IgYaHiko]

📝 Issue Description:

Currently, FingAI only supports Google authentication for signing in.
To make the platform more accessible and developer-friendly, we need to integrate multiple auth providers, specifically GitHub and Facebook.

🎯 Goals:

Add GitHub and Facebook as additional OAuth providers

Keep Google Auth working as the default

Allow users to choose their preferred login method on the sign-in page

Store provider details properly in the database (e.g., provider name, email, UID)

Ensure smooth redirects and token handling

💡 Suggestions (Optional):

Use a unified AuthProvider component with dynamic provider options

Use NextAuth.js or your existing auth logic with Convex/Firebase/Prisma integration

Add clean UI buttons for each provider with proper icons (GitHub, Facebook, Google)

Ensure all providers work across desktop and mobile

🧠 Tech Stack Reference:

Next.js (App Router)

Prisma ORM / Neon DB

Tailwind CSS + Shadcn UI

OAuth (Google, GitHub, Facebook)

🧩 Expected Outcome:

A sleek authentication screen allowing users to sign in via Google, GitHub, or Facebook seamlessly.