[feature]: Realtime work-item updates over the live server (auto-refresh boards/lists without manual reload)

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Summary

Broadcast work-item change events over the existing live (collaboration) server, so that every open board / list / calendar view soft-refreshes automatically when another user (or an API client) creates, updates, drags, archives or deletes a work item — no manual browser refresh needed.

Why should this be worked on?

Plane is built for agile teamwork, but today every work-item view is fetch-on-mount: the kanban/list store fetches once when the page mounts and never revalidates. Concretely:

• User A drags a card to Done; user B's screen keeps showing it under Todo until B manually reloads the page.
• Changes made through the public v1 API (CI bots, integrations) are invisible to everyone watching the board.
• Stale groupings silently mislead stand-ups and triage sessions.

The infrastructure for real-time already ships with CE: apps/live (Hocuspocus + Redis broadcast) powers collaborative page editing. Extending the same channel pattern to work-item events gives instant, multi-instance-safe sync without introducing a second realtime stack:

1. The API emits a lightweight event (project / work item / change type / actor — no work-item data in the payload) after each change, from the single choke point that already records issue activity.
2. The live server relays it to a per-project broadcast channel (issue-events:<project_id>) over the existing Redis extension.
3. Web clients subscribed to that channel ignore their own events, debounce bursts, and soft-refetch the current view with its existing pagination (no loader flash, scroll position kept).

Clients that don't configure the feature see zero change: the whole path is disabled unless an internal shared key is set on both the API and the live server.

Working implementation

A complete, self-contained implementation is attached as a PR: it covers drag & drop re-ordering/state changes, detail edits, creation, bulk delete, archiving, cycle/module membership changes and API-token-driven updates, and has been running on a self-hosted CE deployment.

Start by reviewing the attached implementation and the existing apps/live Hocuspocus and Redis broadcast path. Trace the API change-event choke point and the subscribed board, list, and calendar clients. Done means supported work-item changes trigger debounced soft-refreshes across project views while preserving pagination and scroll position, with the shared-key feature gate disabled by default.