Added

• SSE stale-edit warning: when another session updates an entity that is open for editing, an inline banner warns with Reload / Keep editing options. Also handles remote deletes with auto-close and toast notification.
• Notes contentEditable editor: basic mode notes now use a contentEditable div instead of a textarea. Click rendered content to enter edit mode. Cmd+S / Ctrl+S keyboard shortcut to save.
• Notes deep links: selecting a note updates the URL hash (#note=<id>). F5 or sharing the URL reopens the note. Copy link button in the note toolbar. Browser back/forward navigation supported via hashchange listener.

Fixed

• Marketing plans missing from feature visibility settings and breadcrumb navigation. The feature was fully implemented but invisible in the UI.