Addresses the 2 findings from /code-review high on 726c382:
- NavigationProvider: openChannel/enterYtSearch no longer markDirty. A sub-view is an
overlay, not a page change — the page re-hydrate's replaceState already spreads the
_chan/_yt marker, so the overlay survives on top of the RESTORED page. Removing the
markDirty lets a fresh tab still restore the stored landing page under a pre-pin overlay
(previously it stuck on the default). setPage keeps markDirty (a real navigation).
- useFilterState.dom.test.ts: model a mutable pinned account and add 3 integration tests —
null->id re-hydrate adopts the stored map, the migrate seed carries a legacy value forward
on re-hydrate when the key is empty, and a pre-pin edit is preserved (markDirty guard).
gate-green: vite build + vitest 120 + eslint-0 + knip + prettier. Fresh-tab restore re-E2E'd
(lands on Plex with full state, zero console errors).