Add task count badges to sidebar navigation items #3
Description
Display count badges next to navigation items showing how many tasks are in each view. For example, "In Progress (5)" or "Do Quadrant (12)" helps users quickly assess workload at a glance. This is a visual enhancement that improves information scannability.
Acceptance Criteria
- Count badges appear next to sidebar navigation items (Projects, Goals, Activity, etc.)
- Badges update in real-time as tasks are created, deleted, or moved
- Badge styling follows shadcn/ui Badge component conventions
- Badges respect task filters and kanban status (e.g., only count tasks in current view)
- Works with responsive design (badges scale appropriately on mobile)
- Unit tests verify badge count accuracy across state changes