[S4] Add 401 response handler to clear JWT and redirect to login

[Akshola00]

Description

If any API call returns a 401, the stored JWT is invalid or expired. Automatically clear it and redirect the user to the login page.

Deliverables

• API client catches 401 responses globally
• Calls clearJwt() to remove the stored token
• Calls walletStore.disconnectWallet() to clear wallet state
• Redirects to /login using Next.js router.push
• Does not redirect for 401s on the auth endpoints themselves (/auth/challenge, /auth/verify)
• npm run build passes

Notes

Depends on #58 (interceptor) and #74 (walletStore disconnect update).

[Lazaruster]

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

i will love to work on this issue

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

[Zinai10]

@Zinai10 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hi Maintainer! I would like to work on this issue

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Zinai10 to this issue.

[drips-wave]

Congratulations, @Zinai10! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 30, 2026.

🧑‍💻 @Zinai10: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

Warning

When opening a PR, please link it to this issue to ensure it gets tracked accurately. Points are awarded when this issue is marked as completed by the maintainer.

🤠 Repo maintainers: Please keep an eye on the contributor's progress and review their work before the due date. You can manage this issue, including adjusting its complexity and points, here.

🌊 Happy Wave 🌊