Three distinct bugs caused infinite OIDC redirect loops:
1. After logout, navigating to /login with no signal to suppress the
auto-redirect caused the login page to immediately re-trigger the
OIDC flow. Fixed by passing `{ state: { noRedirect: true } }` via
React Router's navigation state (not URL params, which were fragile
due to async cleanup timing) from all logout call sites.
2. On the OIDC callback page (/login?oidc_code=...), App.tsx's
mount-level loadUser() fired concurrently with the LoginPage's
exchange fetch. The App-level call had no cookie yet and got a 401,
which (if it resolved after the successful exchange loadUser()) would
overwrite isAuthenticated back to false. Fixed by skipping loadUser()
in App.tsx when the initial path is /login.
3. React 18 StrictMode double-invokes useEffect. The first run called
window.history.replaceState to clean the oidc_code from the URL
before starting the async exchange, so the second run saw no
oidc_code and fell through to the getAppConfig auto-redirect, firing
window.location.href = '/api/auth/oidc/login' before the exchange
could complete. Fixed by adding a useRef guard to prevent
double-execution and moving replaceState into the fetch callbacks so
the URL is only cleaned after the exchange resolves.
Also adds login.oidcLoggedOut translation key in all 14 languages to
show "You have been logged out" instead of the generic OIDC-only
message when landing on /login after an intentional logout.
Closes#491
47b880221d