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/stores/useUIStore.ts

@@ -577,6 +577,7 @@ interface UIStore {
 
   favoriteModels: Array<{ providerID: string; modelID: string }>;
   hiddenModels: Array<{ providerID: string; modelID: string }>;
+  providerOrder: string[];
   collapsedModelProviders: string[];
   recentModels: Array<{ providerID: string; modelID: string }>;
   recentAgents: string[];
@@ -727,6 +728,7 @@ interface UIStore {
     overProviderID: string,
     overModelID: string,
   ) => void;
+  setProviderOrder: (orderedProviderIDs: string[]) => void;
   toggleHiddenModel: (providerID: string, modelID: string) => void;
   isHiddenModel: (providerID: string, modelID: string) => boolean;
   hideAllModels: (providerID: string, modelIDs: string[]) => void;
@@ -861,6 +863,7 @@ export const useUIStore = create<UIStore>()(
         mobileKeyboardMode: getStoredMobileKeyboardMode(),
         favoriteModels: [],
         hiddenModels: [],
+        providerOrder: [],
         collapsedModelProviders: [],
         recentModels: [],
         recentAgents: [],
@@ -1735,6 +1738,17 @@ export const useUIStore = create<UIStore>()(
           });
         },
 
+        setProviderOrder: (orderedProviderIDs) => {
+          set((state) => {
+            const next = orderedProviderIDs.filter((id) => typeof id === 'string' && id.length > 0);
+            const current = state.providerOrder;
+            if (current.length === next.length && current.every((id, index) => id === next[index])) {
+              return state;
+            }
+            return { providerOrder: next };
+          });
+        },
+
         toggleHiddenModel: (providerID, modelID) => {
           set((state) => {
             const exists = state.hiddenModels.some(
@@ -2217,6 +2231,7 @@ export const useUIStore = create<UIStore>()(
           cornerRadius: state.cornerRadius,
           favoriteModels: state.favoriteModels,
           hiddenModels: state.hiddenModels,
+          providerOrder: state.providerOrder,
           collapsedModelProviders: state.collapsedModelProviders,
           recentModels: state.recentModels,
           recentAgents: state.recentAgents,