CORS_ORIGINS was hardcoded in docker-compose.yml, silently overriding .env
and breaking login for users who change the frontend port. It now comes
from .env exclusively, with a clear comment in .env.example.
Login page now distinguishes network errors (CORS/offline) from wrong
credentials, and footer correctly references .env instead of config.yml.
Implements issue #5. Off by default; set LIVEVIEW_KEY in .env to enable.
No JWT required — key-based auth via ?key= query param.
Returns 403 when disabled or key is wrong.
Read-only ReactFlow canvas (pan/zoom, no editing).
Standalone mode loads from localStorage without a key.
Includes 8 backend tests and 9 frontend tests.