Mousehole: Unauthenticated HTTP/WebSocket boundary exposes and mutates MAM cookie state

Mousehole is a background service to update a seedbox IP for MAM and web app to manage it. Prior to version 0.4.05, Mousehole's HTTP/WebSocket management boundary is reachable without application-layer authentication or browser/LAN provenance checks. The service stores a MyAnonamouse (MAM) session cookie in state and reuses the same cookie-bearing serialization for persisted state, public API responses, and WebSocket state updates. Any client that can reach the published Mousehole port can read cookie-bearing state, connect to WebSocket state updates, replace the stored cookie, or force MAM update side effects. The deployment examples publish port 5010 broadly with Docker's `5010:5010` syntax, which can make the issue reachable on mixed-trust LAN/VPN interfaces. Version 0.4.0 patches the issue.