feat(settings): rework settings page; remove unused SkeletonLoader/StorageManagement

Settings page refactor plus supporting docs (requirements, ux-flows,
traceability) and the frontend-domain-model spec with implementation-status
banner. Removes SkeletonLoader and StorageManagement components (no remaining
references).

docs/requirements.md

@@ -67,6 +67,7 @@ For a narrative overview of the system design, see
 | UR-054 | Reach account actions (Settings, Downloads, Display preferences, Sign out) from every authenticated screen via a single account menu anchored to the user's name, identical on desktop and mobile (see [ux-flows.md §1.2](ux-flows.md)) | High | Done |
 | UR-055 | Browse downloaded media as an offline-scoped library — reusing the same library grids, cards, and detail pages as online browsing, showing only libraries/containers with downloaded content — with the transfer-progress list demoted to a secondary "Transfers" view (see [ux-flows.md §7.2](ux-flows.md)) | High | Planned |
 | UR-056 | See how much disk each downloaded item/album/series consumes, in familiar rounded units shown on the card and detail page, with a device total on the Downloaded surface and a reclaim amount stated at the point of removal (see [ux-flows.md §7.3.1](ux-flows.md)) | Medium | Planned |
+| UR-057 | Settings apply the instant a control is changed — no "Save" button and no save/dirty state — so leaving the page never loses a change; sliders show a live readout while dragging but persist on release (see [ux-flows.md §8.1](ux-flows.md)) | Medium | Done |
 
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@@ -235,6 +236,7 @@ Internal architecture, components, and application logic.
 | DR-083 | Downloaded browse reuses library grids, cards, and detail pages via the offline-scoped source; omits libraries/containers with no downloaded content; badges partially- vs fully-downloaded containers; play uses the local file; remove available at item/album/season/series level | UI | UR-055 | Planned |
 | DR-084 | Transfers view renders only in-flight rows (downloading/queued/paused/failed/waiting-for-WiFi) with Pause/Resume/Cancel/Retry; completed transfers leave the view and appear in Downloaded | UI | UR-055 | Planned |
 | DR-085 | Per-item on-disk size: stat downloaded files, aggregate to album/season/series subtotals and a device total, format in consistent rounded human units; surface size on cards and detail pages, the device total on the Downloaded surface, and a reclaim figure in the remove confirmation | Downloads | UR-056 | Planned |
+| DR-086 | Settings page persists each control on change via per-group writers (`playerSetAudioSettings` / `playerSetVideoSettings` / `updateCacheConfig`) rather than a batch Save action; slider controls persist on `change` (pointer release) not each `input` tick; no Save button, `saving`, or `saveMessage` state | Settings | UR-057 | Done |
 
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@@ -300,6 +302,7 @@ Internal architecture, components, and application logic.
 | UR-054 | - | DR-075, DR-076, DR-077 |
 | UR-055 | - | DR-081, DR-082, DR-083, DR-084 |
 | UR-056 | - | DR-085 |
+| UR-057 | - | DR-086 |
 
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