feat(frontend): Implement Phase 1 - ProjectManagement API Client & Hooks

Add complete API integration for ProjectManagement module:
- Epics, Stories, Tasks API clients
- React Query hooks for all entities
- Updated type definitions to match backend API
- API test page for connection verification

Changes:
- Update lib/api/config.ts: Add all ProjectManagement endpoints
- Update types/project.ts: Match backend API models (Epic, Story, Task)
- Create lib/api/pm.ts: API clients for Epics, Stories, Tasks
- Create lib/hooks/use-epics.ts: React Query hooks for Epic CRUD
- Create lib/hooks/use-stories.ts: React Query hooks for Story CRUD
- Create lib/hooks/use-tasks.ts: React Query hooks for Task CRUD
- Create app/(dashboard)/api-test/page.tsx: API connection test page

Features:
- Full CRUD operations for Epics, Stories, Tasks
- Status change and assignment operations
- Optimistic updates for better UX
- Error handling with toast notifications
- Query invalidation for cache consistency

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

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

lib/api/pm.ts

@@ -0,0 +1,109 @@
+import { api } from './client';
+import type {
+  Epic,
+  CreateEpicDto,
+  UpdateEpicDto,
+  Story,
+  CreateStoryDto,
+  UpdateStoryDto,
+  Task,
+  CreateTaskDto,
+  UpdateTaskDto,
+  WorkItemStatus,
+} from '@/types/project';
+
+// ==================== Epics API ====================
+export const epicsApi = {
+  list: async (projectId?: string): Promise<Epic[]> => {
+    const params = projectId ? { projectId } : undefined;
+    return api.get('/api/v1/epics', { params });
+  },
+
+  get: async (id: string): Promise<Epic> => {
+    return api.get(`/api/v1/epics/${id}`);
+  },
+
+  create: async (data: CreateEpicDto): Promise<Epic> => {
+    return api.post('/api/v1/epics', data);
+  },
+
+  update: async (id: string, data: UpdateEpicDto): Promise<Epic> => {
+    return api.put(`/api/v1/epics/${id}`, data);
+  },
+
+  delete: async (id: string): Promise<void> => {
+    return api.delete(`/api/v1/epics/${id}`);
+  },
+
+  changeStatus: async (id: string, status: WorkItemStatus): Promise<Epic> => {
+    return api.put(`/api/v1/epics/${id}/status`, { status });
+  },
+
+  assign: async (id: string, assigneeId: string): Promise<Epic> => {
+    return api.put(`/api/v1/epics/${id}/assign`, { assigneeId });
+  },
+};
+
+// ==================== Stories API ====================
+export const storiesApi = {
+  list: async (epicId?: string): Promise<Story[]> => {
+    const params = epicId ? { epicId } : undefined;
+    return api.get('/api/v1/stories', { params });
+  },
+
+  get: async (id: string): Promise<Story> => {
+    return api.get(`/api/v1/stories/${id}`);
+  },
+
+  create: async (data: CreateStoryDto): Promise<Story> => {
+    return api.post('/api/v1/stories', data);
+  },
+
+  update: async (id: string, data: UpdateStoryDto): Promise<Story> => {
+    return api.put(`/api/v1/stories/${id}`, data);
+  },
+
+  delete: async (id: string): Promise<void> => {
+    return api.delete(`/api/v1/stories/${id}`);
+  },
+
+  changeStatus: async (id: string, status: WorkItemStatus): Promise<Story> => {
+    return api.put(`/api/v1/stories/${id}/status`, { status });
+  },
+
+  assign: async (id: string, assigneeId: string): Promise<Story> => {
+    return api.put(`/api/v1/stories/${id}/assign`, { assigneeId });
+  },
+};
+
+// ==================== Tasks API ====================
+export const tasksApi = {
+  list: async (storyId?: string): Promise<Task[]> => {
+    const params = storyId ? { storyId } : undefined;
+    return api.get('/api/v1/tasks', { params });
+  },
+
+  get: async (id: string): Promise<Task> => {
+    return api.get(`/api/v1/tasks/${id}`);
+  },
+
+  create: async (data: CreateTaskDto): Promise<Task> => {
+    return api.post('/api/v1/tasks', data);
+  },
+
+  update: async (id: string, data: UpdateTaskDto): Promise<Task> => {
+    return api.put(`/api/v1/tasks/${id}`, data);
+  },
+
+  delete: async (id: string): Promise<void> => {
+    return api.delete(`/api/v1/tasks/${id}`);
+  },
+
+  changeStatus: async (id: string, status: WorkItemStatus): Promise<Task> => {
+    return api.put(`/api/v1/tasks/${id}/status`, { status });
+  },
+
+  assign: async (id: string, assigneeId: string): Promise<Task> => {
+    return api.put(`/api/v1/tasks/${id}/assign`, { assigneeId });
+  },
+};