feat: inherit model-picker reorder/accordion persistence and shift-delete from otto-ui (#1833)

* feat(model-picker): drag-to-reorder providers and persist accordion state

Ports two model/provider picker QoL features from otto-ui:
- Persist collapsed state of picker sections (favorites, recent, each
  provider) via a new persisted zustand store so collapse survives
  remounts and reloads, shared across every picker surface.
- Desktop drag-to-reorder of provider sections (whole header as the
  mouse activator, 8px threshold so a plain click still toggles
  collapse), with the order persisted in useUIStore.providerOrder and
  applied across ModelControls, ModelMultiSelect and ModelSelector.

Co-authored-by: Serhii Dziupin <makeittech@users.noreply.github.com>

* feat(sessions): shift-click quick action hard-deletes thread without prompt

Ports the shift-quick-delete feature from otto-ui. The sidebar quick
action (normally archive) becomes a no-prompt hard delete while Shift is
held: the icon switches to a trash bin, the affordance turns destructive,
and the click bypasses the confirmation dialog via a new skipConfirm
source flag. A shared useShiftKeyHeld hook (single window listener set,
useSyncExternalStore) keeps only the small action button re-rendering on
Shift state changes, and resets on window blur so the affordance can't
get stuck after alt-tab.

Co-authored-by: Serhii Dziupin <makeittech@users.noreply.github.com>

---------

Co-authored-by: Serhii Dziupin <makeittech@users.noreply.github.com>

packages/ui/src/components/chat/ModelControls.tsx

@@ -366,6 +366,8 @@ export const ModelControls: React.FC<ModelControlsProps> = ({
 
     const toggleFavoriteModel = useUIStore((state) => state.toggleFavoriteModel);
     const reorderFavoriteModel = useUIStore((state) => state.reorderFavoriteModel);
+    const providerOrder = useUIStore((state) => state.providerOrder);
+    const setProviderOrder = useUIStore((state) => state.setProviderOrder);
     const isFavoriteModel = useUIStore((state) => state.isFavoriteModel);
     const addRecentModel = useUIStore((state) => state.addRecentModel);
     const addRecentAgent = useUIStore((state) => state.addRecentAgent);
@@ -2368,6 +2370,9 @@ export const ModelControls: React.FC<ModelControlsProps> = ({
                                 )}
                                 reorderFavoriteAriaLabel={t('chat.modelControls.reorderFavoriteAria')}
                                 reorderFavoriteTitle={t('chat.modelControls.reorderFavoriteTitle')}
+                                providerOrder={providerOrder}
+                                onReorderProvider={setProviderOrder}
+                                reorderProviderTitle={t('chat.modelControls.reorderProviderTitle')}
                                 footerContent={(activeEntry) => {
                                     const activeHasThinkingVariants = activeEntry
                                         ? getModelVariantOptions(activeEntry.providerID, activeEntry.modelID).length > 0