feat: implement admin signup flow

[zintarh]

Overview

This PR implements the full multi-step Admin Signup Flow, focusing on the flow logic for both email-based registration and wallet-based signup via StarkNet React. The admin signup process is critical for onboarding users with elevated privileges, and this implementation ensures clarity, security, and future extensibility of the registration pipeline.

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https://www.loom.com/share/8fd6b23512f744f6bedfc80c983f246c?sid=40f724c8-b022-4da6-ab2f-d7fea90658e4

What’s Included

Admin Signup Flow Landing Screen

• Designed and implemented a central onboarding page where users(admins) can choose between:

  • Signing up via Email
  • Signing up via Wallet (StarkNet React)

📧 Email-Based Signup Flow (3 screens)

1. Email Entry Screen – User inputs email for verification.
2. Verification Notice Screen – User is notified that a verification link has been sent.
3. Pending Approval Screen – Once email is verified, user sees a "pending approval" status awaiting super admin activation.

Wallet-Based Signup Flow (4 screens)

1. Wallet Connect Prompt – Integration with StarkNet React to allow wallet selection and connection.
2. Wallet Progress Screen – Confirms wallet signature and retrieves address.
3. Signature Screen – Optionally collects metadata or additional admin details tied to wallet.
4. Succss Screen – Similar to email flow, informs user their request is under review.

✅ Note: All available wallets from Starknet React are now dynamically displayed in the wallet signup flow for better UX.

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Security Considerations

• No direct admin access granted on signup — Approval must come from existing system admin.
• Email uniqueness validation has been considered at the UI layer (backend pending integration).
• Screens include visual cues to inform users that their request is not yet fully activated.
• Placeholder for audit logging and welcome email trigger added for backend integration handoff.

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Design Reference

All screens were built following the design specs provided in Figma.

How to Test

• Visit /admin/signup route
• Test both signup flows (email and wallet)
• Use mock email and wallet addresses to simulate flow
• Ensure transitions between steps are smooth and responsive

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closes #58

[Iwueseiter]

LGTM!
Great work @zintarh