feat(frontend): Implement Task management components - Sprint 4 Story 2

Add complete Task CRUD UI for Story detail page with inline creation,
status toggling, filtering, and sorting capabilities.

Changes:
- Created TaskList component with filters, sorting, and progress bar
- Created TaskCard component with checkbox status toggle and metadata
- Created TaskQuickAdd component for inline Task creation
- Added shadcn/ui checkbox and alert components
- All components use existing Task hooks (useTasks, useCreateTask, etc.)

Components:
- components/tasks/task-list.tsx (150 lines)
- components/tasks/task-card.tsx (160 lines)
- components/tasks/task-quick-add.tsx (180 lines)
- components/ui/checkbox.tsx (shadcn/ui)
- components/ui/alert.tsx (shadcn/ui)

Features:
- Task list with real-time count and progress bar
- Filter by: All, Active, Completed
- Sort by: Recent, Alphabetical, Status
- Checkbox toggle for instant status change (optimistic UI)
- Inline Quick Add form for fast Task creation
- Priority badges and metadata display
- Loading states and error handling
- Empty state messaging

Sprint 4 Story 2: Task Management in Story Detail
Task 3: Implement TaskList, TaskCard, TaskQuickAdd components

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

package.json

@@ -30,6 +30,7 @@
     "@microsoft/signalr": "^9.0.6",
     "@radix-ui/react-alert-dialog": "^1.1.15",
     "@radix-ui/react-avatar": "^1.1.11",
+    "@radix-ui/react-checkbox": "^1.3.3",
     "@radix-ui/react-dialog": "^1.1.15",
     "@radix-ui/react-dropdown-menu": "^2.1.16",
     "@radix-ui/react-label": "^2.1.7",