[Bug] Session token expiry causes silent GraphQL failures — RefreshTokenExpired not surfaced to user

Summary

When the Keycloak session token expires, RefreshTokenExpired warnings appear in the console but no UI feedback is shown to the user. GraphQL queries silently fail — pages appear loaded but data is missing or stale. Additionally, a backend TypeError is thrown during token validation.

Impact

• Users remain on what looks like a functional page but data is not loading
• No session expiry banner, no redirect to login, no retry prompt

Fix

1. Intercept RefreshTokenExpired in the auth middleware and redirect to login with a "Your session has expired" message
2. Fix the backend TypeError in the token validation path
3. Add a global GraphQL error handler that catches auth errors and prompts re-login

Report ref: AUTH-001 · Severity: HIGH