Dataroom routes were reading x-investor-id from request headers which
the middleware sets as response headers — these don't reach route handlers
when the admin fallback path runs (NextResponse.next() without header).
Switch to getSessionFromCookie() consistent with all other investor routes.
Auth page DSGVO footer switched from absolute bottom-0 to normal flow
so the expanded Art. 13 notice doesn't overlap the login card.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>