[BUG]: Auth failure redirects to /login, but no /login route exists

### Bug Description

## Description
`frontend/src/context/authContext.tsx` line 69 navigates to `/login` when token verification fails, but `App.tsx` defines no `/login` route. The navigation falls through the `*` catch-all (App.tsx line 105) and lands on `/`.

## Impact
A user with an expired/invalid token is silently dumped on the home page instead of the auth screen, with no indication they were logged out.

## Suggested Fix
Redirect to the actual auth route (`/auth` — see App.tsx route list), or add a `/login` alias route.

### Steps to Reproduce

_No response_

### Logs and Screenshots

_No response_

### Environment Details

_No response_

### Impact

High - Major feature is broken

### Code of Conduct

- [x] I have joined the [Discord server](https://discord.gg/hjUhu33uAn) and will post updates there
- [x] I have searched existing issues to avoid duplicates

Start in frontend/src/context/authContext.tsx at line 69, then inspect the route list and catch-all in App.tsx, including line 105. Update the failed-token navigation to use the existing /auth route, and verify that an expired or invalid token reaches the auth screen instead of /.

Written by the indexing model from the issue text.