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/hooks/use-tasks.ts

@@ -0,0 +1,163 @@
+import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query';
+import { tasksApi } from '@/lib/api/pm';
+import type { Task, CreateTaskDto, UpdateTaskDto, WorkItemStatus } from '@/types/project';
+import { toast } from 'sonner';
+
+// ==================== Query Hooks ====================
+export function useTasks(storyId?: string) {
+  return useQuery<Task[]>({
+    queryKey: ['tasks', storyId],
+    queryFn: async () => {
+      console.log('[useTasks] Fetching tasks...', { storyId });
+      try {
+        const result = await tasksApi.list(storyId);
+        console.log('[useTasks] Fetch successful:', result);
+        return result;
+      } catch (error) {
+        console.error('[useTasks] Fetch failed:', error);
+        throw error;
+      }
+    },
+    staleTime: 5 * 60 * 1000, // 5 minutes
+    retry: 1,
+  });
+}
+
+export function useTask(id: string) {
+  return useQuery<Task>({
+    queryKey: ['tasks', id],
+    queryFn: () => tasksApi.get(id),
+    enabled: !!id,
+  });
+}
+
+// ==================== Mutation Hooks ====================
+export function useCreateTask() {
+  const queryClient = useQueryClient();
+
+  return useMutation({
+    mutationFn: (data: CreateTaskDto) => tasksApi.create(data),
+    onSuccess: (newTask) => {
+      // Invalidate all task queries
+      queryClient.invalidateQueries({ queryKey: ['tasks'] });
+
+      // Also invalidate story details
+      queryClient.invalidateQueries({ queryKey: ['stories', newTask.storyId] });
+
+      toast.success('Task created successfully!');
+    },
+    onError: (error: any) => {
+      console.error('[useCreateTask] Error:', error);
+      toast.error(error.response?.data?.detail || 'Failed to create task');
+    },
+  });
+}
+
+export function useUpdateTask() {
+  const queryClient = useQueryClient();
+
+  return useMutation({
+    mutationFn: ({ id, data }: { id: string; data: UpdateTaskDto }) =>
+      tasksApi.update(id, data),
+    onMutate: async ({ id, data }) => {
+      await queryClient.cancelQueries({ queryKey: ['tasks', id] });
+
+      const previousTask = queryClient.getQueryData<Task>(['tasks', id]);
+
+      queryClient.setQueryData<Task>(['tasks', id], (old) => ({
+        ...old!,
+        ...data,
+      }));
+
+      return { previousTask };
+    },
+    onError: (error: any, variables, context) => {
+      console.error('[useUpdateTask] Error:', error);
+
+      if (context?.previousTask) {
+        queryClient.setQueryData(['tasks', variables.id], context.previousTask);
+      }
+
+      toast.error(error.response?.data?.detail || 'Failed to update task');
+    },
+    onSuccess: () => {
+      toast.success('Task updated successfully!');
+    },
+    onSettled: (_, __, variables) => {
+      queryClient.invalidateQueries({ queryKey: ['tasks', variables.id] });
+      queryClient.invalidateQueries({ queryKey: ['tasks'] });
+    },
+  });
+}
+
+export function useDeleteTask() {
+  const queryClient = useQueryClient();
+
+  return useMutation({
+    mutationFn: (id: string) => tasksApi.delete(id),
+    onSuccess: (_, id) => {
+      queryClient.invalidateQueries({ queryKey: ['tasks'] });
+      queryClient.removeQueries({ queryKey: ['tasks', id] });
+      toast.success('Task deleted successfully!');
+    },
+    onError: (error: any) => {
+      console.error('[useDeleteTask] Error:', error);
+      toast.error(error.response?.data?.detail || 'Failed to delete task');
+    },
+  });
+}
+
+export function useChangeTaskStatus() {
+  const queryClient = useQueryClient();
+
+  return useMutation({
+    mutationFn: ({ id, status }: { id: string; status: WorkItemStatus }) =>
+      tasksApi.changeStatus(id, status),
+    onMutate: async ({ id, status }) => {
+      await queryClient.cancelQueries({ queryKey: ['tasks', id] });
+
+      const previousTask = queryClient.getQueryData<Task>(['tasks', id]);
+
+      queryClient.setQueryData<Task>(['tasks', id], (old) => ({
+        ...old!,
+        status,
+      }));
+
+      return { previousTask };
+    },
+    onError: (error: any, variables, context) => {
+      console.error('[useChangeTaskStatus] Error:', error);
+
+      if (context?.previousTask) {
+        queryClient.setQueryData(['tasks', variables.id], context.previousTask);
+      }
+
+      toast.error(error.response?.data?.detail || 'Failed to change task status');
+    },
+    onSuccess: () => {
+      toast.success('Task status changed successfully!');
+    },
+    onSettled: (_, __, variables) => {
+      queryClient.invalidateQueries({ queryKey: ['tasks', variables.id] });
+      queryClient.invalidateQueries({ queryKey: ['tasks'] });
+    },
+  });
+}
+
+export function useAssignTask() {
+  const queryClient = useQueryClient();
+
+  return useMutation({
+    mutationFn: ({ id, assigneeId }: { id: string; assigneeId: string }) =>
+      tasksApi.assign(id, assigneeId),
+    onSuccess: (_, variables) => {
+      queryClient.invalidateQueries({ queryKey: ['tasks', variables.id] });
+      queryClient.invalidateQueries({ queryKey: ['tasks'] });
+      toast.success('Task assigned successfully!');
+    },
+    onError: (error: any) => {
+      console.error('[useAssignTask] Error:', error);
+      toast.error(error.response?.data?.detail || 'Failed to assign task');
+    },
+  });
+}