Add ygo (Go port of Yjs) to Ports to other languages

[bnimit]

Adds a Go port of Yjs to the Ports to other languages page.

About the port

• Repository: https://github.com/reearth/ygo
• License: MIT
• Latest release: v1.19.0
• Maintenance: Active. In production at Re:Earth (Eukarya). Semver-stable v1.x public API.

Scope

• Full CRDT engine — YArray, YMap, YText (with rich-text Format + InsertEmbed), YXml*. Arbitrarily nested types; recursive ToJSON unwrap.
• Wire-format compatible with Yjs JS — V1 and V2 update codecs, awareness, snapshot. Verified by a JS↔Go interop fixture suite that round-trips through `node` against the Yjs reference.
• Cross-reference audit complete — closed a 10-issue audit against Yjs JS and yrs across the v1.9.0–v1.15.0 cycle, covering YText format markers, observer event shapes (YArrayEvent.Delta, YMapEvent.Keys with action/oldValue, YTextEvent embeds), transaction-commit housekeeping (auto-GC, split re-merge), snapshot semantics, and YATA conflict-scan edges.
• Sync transports — WebSocket and HTTP. WebSocket server is a drop-in for Hocuspocus-aware clients at the protocol-extension (message types 4-10), lifecycle (OnLoadDocument / OnFirstPeer / OnLastPeer / OnUnloadDocument), and outbound-webhook layers (provider/webhook subpackage with HMAC signing + debounce + bounded retry).
• Production hardening — UndoManager, structured slog logging, ctx-aware methods, panic-safe transactions and hooks, DoS caps on awareness state and pending-items queue, semaphore-backed connection limits, `crypto/rand` ClientID.

Changes

Single edit to `ecosystem/ports-to-other-languages.md`: one `{% embed %}` block following the existing format. No other files affected.

[bnimit]

Friendly bump — refreshed the description with the current state (v1.19.0, audit complete, Hocuspocus parity). Happy to address anything before merge, and no rush. Thanks for taking a look when you have time.