Add a backlog design note for making page-tree realtime updates
server-authoritative instead of client-relayed.
Problem: page content syncs via Yjs/Hocuspocus (server-authoritative),
but tree create/move/delete is broadcast by the originating browser only,
so non-UI creation paths (AI agent, MCP, REST API, import) and lost-event
races leave other clients' sidebars stale.
The note specifies a WsService.emitTreeEvent broadcaster, WsTreeService
broadcast helpers, a PageWsListener on PAGE_CREATED/SOFT_DELETED/DELETED/
MOVED/RESTORED, event-payload enrichment to avoid the in-transaction
re-fetch race, a dedicated PAGE_MOVED event, removal of the client relay,
plus edge cases, work breakdown, tests, alternatives and open questions.
850d9ada22