Proofing Gallery 0.6.1

• keep virtualized public-gallery rows below immersive headers on desktop and
  mobile so every image remains visible and interactive
• preserve guest feedback actions while collaboration updates are delayed or
  temporarily rate-limited, including fast interactions during initialization
• let compact culling controls scroll out of the way while keeping the photo
  and bottom filmstrip together inside the viewport
• cover automatic side and bottom filmstrip placement in the real Nextcloud
  browser flow and reset the Docker gateway during local E2E preparation