handleMessage became a no-op and PageWsListener intentionally ignored
PAGE_UPDATED, so a rename/icon change (client operation:updateOne) was no longer
rebroadcast -> other clients saw stale title/icon in the sidebar+breadcrumbs
until a reload (create/duplicate/restore were covered; updateOne regressed).
Add a server-authoritative onPageUpdated handler: PageService.update detects a
real title/icon change (DTO carries the field AND value differs; no-op/content-
only saves excluded) and attaches a treeUpdate snapshot to PAGE_UPDATED; the
listener broadcasts a tree updateOne via the restriction-aware emitTreeEvent
(so a restricted page's title never leaks). Content-only saves attach nothing.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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