Portal: Supabase realtime websocket handshake fails (wss://oma.lanetti.fi/realtime/v1/websocket)

Imported from GitHub issue El-SaMa/oma#230 by @El-SaMa.

Seen on /apps/uptime/status in the 2026-10-15 headless run: WebSocket connection to wss://oma.lanetti.fi/realtime/v1/websocket?... failed: Error during WebSocket handshake (unexpected response). The same-origin Supabase proxy apparently does not pass the WebSocket upgrade for /realtime/v1, so any realtime subscription in the portal never connects.

Check the edge/NPM and app proxy config for Upgrade/Connection headers on /realtime/v1, then confirm a 101 Switching Protocols.