Room list: add drag and drop of sections to reorder them (#33606)

* feat(rls): centralize room-list section ordering via getOrderedSections

Introduce a single source of truth for the ordered list of section
tags (defaults + custom) in section.ts. RoomListStoreV3 no longer
hard-codes the default tag order — it asks section.ts.

* feat(vm): add section reorder logic to RoomListStoreV3 and view model

* refactor(sc): extract RoomListSectionHeaderContent from RoomListSectionHeaderView

* feat(sc): add drag-and-drop reordering for room-list sections

* test(sc): update existing tests

* test: add new tests

* test(sc): add snapshot test for overlay

* test(e2e): add playright test for dnd of sections

* feat: tweak opacity

* fix: section detection when dragged

* feat: use relative position in section order

* chore: move style to room list section header view

* test: add e2e test for moving section before another

* feat: make favourite and low priority no draggable

* test: remove deprecated e2e test

* fix: type correctly dnd provider and hooks

* fix: use String instead of casting to string

* fix: wrong a11y attributes on section header

* test: fix keyboard navigation e2e tests

* feat: use custom a11y announcement for dnd

* fix: add aria-hidden to the overlay

* chore: remove duplicated code in a11Y announcement

* fix: increase keyboard drag offset

* fix: tests

* fix: virtuoso computed item key

* fix: aria-expanded double annoncement why dragging

* fix: re-add screen reader instructions

* chore: remove unused import

* fix: reduce keyboard drag offset

* fix: improve text readback on unread section

* feat: use a custom a11y plugin instead of buitin a11y plugin

* chore: formatting

* test: fix incorrect tests

* chore: use randomUUID

* fix: try to make test working

* fix: put back mock

* fix: circular import

* Revert "fix: circular import"

This reverts commit 6c69313ade9ed2ab17a4622c692b435fbdb94ad2.

* chore: add @dnd-kit/abstract to optimizeDeps.include

* test: fix e2e tests

* fix: disable interaction with section when dragging

* fix: be more explicit if the section will be dropped before or after

* fix: add info that space is dropping too

* fix: scroll to dropped section

* test: fix virtualized room list test

* chore: update lang

* chore: fix dead code analyze

* test: add provider section story

* fix: lang

* fix: again lang...

* fix: improve voice over on chrome

* test: upate snapshot

* fix: add readback when a section is over a non droppable element

packages/shared-components/src/core/VirtualizedList/virtualized-list.tsx

@@ -413,8 +413,16 @@ export function useVirtualizedList<Item, Context>(
         [handleRef],
     );
 
+    // Key items by id, not position, so react-virtuoso preserves (moves) the existing DOM
+    // node when an item's absolute index shifts — e.g. sections collapsing on drag start removes
+    // the rooms above a header, shifting its index. Without this, Virtuoso's default key is the
+    // index, so the wrapper (and the focused header inside it) remounts, the roving-tabindex effect
+    // refocuses the fresh node, and screen readers re-announce the header mid-drag.
+    const computeItemKey = useCallback((_index: number, item: Item): string => getItemKey(item), [getItemKey]);
+
     return {
         ...virtuosoProps,
+        computeItemKey,
         ref: setRef,
         scrollerRef,
         onKeyDown: keyDownCallback,