feat: Remove Discord for login and setup

[LobeTia]

🔗 Linked issue

Resolves #62

❓ Type of change

• 📖 Documentation (updates to the documentation, readme or JSdoc annotations)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality like performance)
• ✨ New feature (a non-breaking change that adds functionality)
• 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

Uniform login form as a shared component and enables Membership and Admin portal to make user login with magic link
Remove Discord from auth provider for easy setup (and because you don't need a Discord account to administrate your nonprofit)

📝 Checklist

• I have linked an issue or discussion.
• I have updated the documentation accordingly.