Build create/edit portfolio form

[ayshadogo]

Description:

• Create app/dashboard/artist/portfolios/new/page.tsx and .../[id]/edit/page.tsx
• Fields: title, description, category select, tags input
• Drag-and-drop image upload for portfolio items
• Save as draft or publish immediately

---

[Abuh-Bakar]

Hi! I'd like work on this issue. I have experience with Git, Github, React, Next.Js, VS Code, and Frontend Development, and i am confident i can implement the required changes while following the project's contribution guidelines. I'd like the opportunity to work on this issue. Thank You!