Notifications from ctx.ui.notify() and workflow-logger now persist to
.gsd/notifications.jsonl instead of evaporating as transient toasts.
- notification-store: JSONL persistence with 500-entry rotation, atomic
temp+rename rewrites, ref-counted suppress API, disk-synced counters
- notify-interceptor: WeakSet-guarded monkey-patch on ctx.ui.notify
installed at session_start and session_switch
- notification-widget: always-on belowEditor strip showing unread count
- notification-overlay: scrollable Ctrl+Alt+N panel with severity filter
- /gsd notifications command: clear, tail, filter subcommands
- workflow-logger: warnings now also persist to notification store
- web API: GET/DELETE /api/notifications with ?countOnly support
- 16 unit tests covering store, suppress, project isolation, resync
