Description
Allow logged-in users to edit and update their profile details (name, skills, availability, etc.) through the frontend and backend (PUT /api/auth/profile).

Tasks:

• Add “Edit Profile” button to /profile page.
• Create EditProfileForm.jsx (modal or separate page).
• Build form with fields: name, skills, availability.
• On submit → call PUT /api/auth/profile.
• Update local AuthContext user state on success.
• Show success/error alerts.

Acceptance:

• Form prefilled with current user data.
• Updating sends valid request and reflects instantly.
• Handles validation + API errors gracefully.
• Works only for authenticated users.