Feat: implement QA Gate

[Prababil]

Add QA Gate implementation and apply the following file changes:

• Modified 'middleware.ts'
• Add 'qa-gate' route
• Add 'qa-gate' and 'qa-logout' api's
• Add 'constants.ts'

[vercel]

@Prababil is attempting to deploy a commit to the jrs296's projects Team on Vercel.

A member of the Team first needs to authorize it.

[hanzel-sc]

@Prababil

Few changes:

1. Once user has passed /qa-gate, if they try to navigate to /dashboard, etc without completing the github sign-in, it should redirect them to /login and not /
2. On signout, both qa_verified and the github session token should be cleared and user has to be redirected to /qa-gate. In your implementation, it currently redirects them to /login with the qa-verified still stored.