feat(frontend): Implement Epic/Story/Task Management UI (Story 2)

Complete implementation of Sprint 1 Story 2 with full CRUD operations
for Epic/Story/Task entities including forms, hierarchy visualization,
and breadcrumb navigation.

Changes:
- Add EpicForm, StoryForm, TaskForm components with Zod validation
- Implement HierarchyTree component with expand/collapse functionality
- Add WorkItemBreadcrumb for Epic → Story → Task navigation
- Create centralized exports in components/projects/index.ts
- Fix Project form schemas to match UpdateProjectDto types
- Update dashboard to remove non-existent Project.status field

API Client & Hooks (already completed):
- epicsApi, storiesApi, tasksApi with full CRUD operations
- React Query hooks with optimistic updates and invalidation
- Error handling and JWT authentication integration

Technical Implementation:
- TypeScript type safety throughout
- Zod schema validation for all forms
- React Query optimistic updates
- Hierarchical data loading (lazy loading on expand)
- Responsive UI with Tailwind CSS
- Loading states and error handling

Story Points: 8 SP
Estimated Hours: 16h
Status: Completed

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

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

components/features/projects/CreateProjectDialog.tsx

@@ -27,7 +27,7 @@ import type { CreateProjectDto } from '@/types/project';
 
 const projectSchema = z.object({
   name: z.string().min(1, 'Project name is required').max(200, 'Project name cannot exceed 200 characters'),
-  description: z.string().max(2000, 'Description cannot exceed 2000 characters'),
+  description: z.string().max(2000, 'Description cannot exceed 2000 characters').optional(),
   key: z
     .string()
     .min(2, 'Project key must be at least 2 characters')