Adds immich-proxy (search-app) with live search injection, WebSocket
proxying for socket.io, and 10GB upload buffering via Traefik middleware.
Moves Traefik routing from immich-server to proxy. Updates valkey 8→9.
Adds backlog tasks for drone sync and Syncthing reconnection.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
