Removes non-null assertions on householdId/householdName. Users who
haven't joined a household get a fallback name in the sidebar.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Validates session cookie via GET /v1/auth/me, populates event.locals
with benutzer and haushalt, redirects to /login if unauthenticated.
Public routes (/login, /register, /invite) bypass auth.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>