0.4.75

Receptionist (/start and the preview critic); no worker change.

• First-time run-through fixes. Walking through /start as a new user with their own .blend (docs/64 §7): the wait line said "about about 5 seconds"; a key kept in the browser that the server no longer knew produced "unknown or revoked key… POST /v1/keys" (now the page drops it and makes a fresh key); the preview's notes listed "cut by the frame edge" twice (the critic now says each sentence once).