feat: implement wallet connection and JWT authentication flow

[Josue19-08]

🔖 Title

Implement wallet connection and complete JWT authentication flow

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📄 Description

The `SignIn.tsx` and `CreateAccountScreen.tsx` screens exist with full UI and validation, but neither makes any API calls. The "Connect Wallet" button has no `onPress` handler. The authentication flow (nonce → sign → verify → store JWT) needs to be wired up end to end.

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✅ Tasks to complete

• Integrate Freighter or Albedo wallet SDK for Stellar wallet connection in React Native
• Implement wallet connection in `use-sign-in.ts`:
  1. Request wallet public key from connected wallet
  2. Call `POST /auth/nonce` with `{ walletAddress }`
  3. Sign the returned nonce message with the wallet
  4. Call `POST /auth/verify` with `{ walletAddress, signature, nonce }`
  5. Store received `accessToken` and `refreshToken` via `token-storage.ts`
  6. Navigate to main app screen
• Wire up `POST /auth/register` in `use-create-account.ts` with multipart form data (profile image + wallet + username + displayName)
• Create `AuthContext` (React Context) to expose `user`, `isAuthenticated`, `signOut` globally
• Implement sign-out: call `DELETE /auth/logout`, clear secure storage, redirect to sign-in
• Protect authenticated screens: redirect unauthenticated users to sign-in
• Add error handling for wallet not installed, rejected signature, network errors

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📚 Documentation/context for AI

(This link never should removed)
https://github.com/TrustUp-app/TrustUp-API/tree/main/docs

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🗒️ Additional notes

• Depends on the API client layer issue being completed first
• The API uses Ed25519 Stellar signatures — the wallet must sign a plain text nonce string
• Store tokens in `expo-secure-store`, never in AsyncStorage (insecure for credentials)
• Consider deep-link support for wallet redirect flows on mobile

[ekwe7]

I would love to work on this issue. I have experience building production ready applications and collaborating through GitHub workflows. I'll carefully analyze the current implementation, propose a reliable solution, and submit a well-tested PR. My focus is on clean code, maintainability, and timely delivery

[diiabblo]

Hi maintainer, could you please assign this issue to me? I'd like to work on it.

[Dev-sandy1]

Good day. Please can i work on these issue.

[Pidoko257]

@Pidoko257 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Maintainer please approve, am a web developer with years of experience in security,backend and frontend

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Pidoko257 to this issue.

[Daggahh]

@Daggahh has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hi I’d like to work on this issue

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Daggahh to this issue.

[Josue19-08]

Closing in favor of #60.

This issue covers wallet connection (Freighter/Albedo), nonce→sign→verify flow, JWT storage, AuthContext, sign-out, and route protection — which is the exact same scope as #60 (implement auth flow). #60 is the canonical tracking issue for the complete authentication implementation.

Nothing is implemented — use-sign-in.ts still uses setTimeout with no API calls. Track all work in #60.