Profile management and role-based access

[Khan-DevHub]

SUMMARY:
This PR adds role-based access control and profile management features to the backend.

-Added role-based access middleware (role.middleware.js).
-Extended user profile with fields: bio, company, investmentHistory, preferences.
-Implemented PUT /api/users/profile to update profile.
-Added role-specific endpoints: /api/users/investor/dashboard and /api/users/entrepreneur/dashboard.
-Tested all endpoints with Thunder Client for both roles.

Changes:
-backend/controllers/user.controller.js
-backend/middleware/role.middleware.js
-backend/routes/user.routes.js
-backend/models/User.js (profile extension)

Testing:
-Investor token → investor dashboard works, entrepreneur dashboard returns 403.
-Entrepreneur token → entrepreneur dashboard works, investor dashboard returns 403.
-Profile update works for both roles.

[vercel]

@Khan-DevHub is attempting to deploy a commit to the Asakusa's projects Team on Vercel.

A member of the Team first needs to authorize it.

[Khan-DevHub]

Hi @Asakusa-k,

I noticed that the Vercel checks are pending authorization from a team member. Could you please review and authorize the deployment when you have a moment?

The PR is ready to go – all code is working and tested locally with both investor and entrepreneur roles.

Thanks!

[Khan-DevHub]

• Frontend: https://nexus-frontend-gray.vercel.app
• Backend API: https://nexus-production-48da.up.railway.app