Phase 1 of #2126. Six hooks move out of `clients/web/src/App.tsx`, taking
its component body from 4,891 to 4,267 lines with no behavior change:
- useThemeToggle — the light/dark toggle
- useTabUiState — the nine per-screen `ui` objects, the active tab,
the pinned-Protocol ids, and the session reset
- useInspectorStores — the twelve state managers as one create/destroy
lifecycle, their `core/react` hooks, and the
pagination-mode selection
- useExportActions — the eleven Clear / Export / Replay handlers
- useProgressToasts — `notifications/progress` toasts
- useTaskToasts — task-status toasts, the cancel confirmation, the
taskId -> progress map, and the in-flight
tool-call taskId ref
Holding the stores in one slot collapses `setupClientForServer`'s and
`onConfirmRemove`'s dependency arrays from twelve entries to two stable
callbacks; `destroyStores` reads the live set through a ref mirror rather
than the state it also writes.
All six hooks are at 100% on all four coverage dimensions, no `v8 ignore`
needed. Also refreshes the now-stale "~4.5k-line" description of App.tsx
in AGENTS.md and the coverage `include` comment.
Signed-off-by: cliffhall <cliff@futurescale.com>
e42968ba78