* refactor(frontend): add useViewNavigationState hook with tests
* refactor(frontend): wire useViewNavigationState into EditorLayout
* test(frontend): add skipper tier and handleOpenSettings no-arg coverage
* refactor(frontend): extract useTheme hook from EditorLayout
* refactor(frontend): extract useNotifications hook from EditorLayout
* refactor(frontend): extract useContainerStats hook, remove containerStats from useEditorViewState
* refactor(frontend): wire useTheme, useNotifications, useContainerStats into EditorLayout
Removes all extracted effect clusters from EditorLayout.tsx and replaces
them with calls to the three new focused hooks. Extracted code removed:
- theme useState + 2 effects (system dark-mode listener, DOM class sync)
- fetchNotifications, fetchNotificationsRef, markAllRead, deleteNotification,
clearAllNotifications, and 5 notification effects (local WS, nodes refetch,
remote per-node WS, remote cleanup, 60s safety-net poll)
- container stats useEffect with 1.5s flush interval
- formatBytes utility (moved to useContainerStats)
- fetchForNode import (no longer used at this level)
EditorLayout now at 17 useState / 4 useEffect, both under the <20 / <10
acceptance criteria required before the B4-7 shell PR.
Anso