feat: add sorting functionality to KanbanFilters

- Enhanced `KanbanFilters` to include sorting options, allowing users to sort tasks dynamically.
- Implemented dropdown for sorting with options rendered via portal to manage z-index issues.
- Updated `TasksContext` to handle sorting preferences and apply sorting logic to both pinned and regular tasks.
- Added `sortBy` property to `KanbanFilters` and user preferences for persistent sorting settings.

services/user-preferences.ts

@@ -6,6 +6,7 @@ export interface KanbanFilters {
   tags?: string[];
   priorities?: TaskPriority[];
   showCompleted?: boolean;
+  sortBy?: string;
 }
 
 export interface ViewPreferences {