Fix: error page dashboard link points to wrong path (/visa/dashboard → /visas/dashboard)

[coderabbitai]

Summary

The 'Return to Dashboard' button in src/main/resources/templates/error/error.html uses a hardcoded href of /visa/dashboard, which does not match the actual controller mapping. VisaViewController is mapped to /visas (plural), so the link results in a 404.

Expected behaviour

Clicking 'Return to Dashboard' on the error page should navigate the user back to the dashboard without error.

Steps to reproduce

1. Trigger any handled exception (e.g. UnauthorizedException) to land on the error/error view.
2. Click the 'Return to Dashboard' button.
3. Observe a 404 response because /visa/dashboard does not exist.

Suggested fix

Replace the hardcoded href with a Thymeleaf expression that resolves to the correct path:

<a th:href="@{/visas/dashboard}" class="btn-back">
    Return to Dashboard
</a>

Also remove the stale TODO comment on the line above.

Additional context

• Raised in PR Feature/error page #38 review: Feature/error page #38 (comment)
• Once Spring Security is wired in, currentUserId will also need to be resolved from the security context rather than passed as a request parameter (see existing deferred work on VisaViewController).

Requested by @eeebbaandersson.