feat(frontend): Implement Issue management and Kanban board

Add comprehensive Issue management functionality with drag-and-drop Kanban board.

Changes:
- Created Issue API client (issues.ts) with CRUD operations
- Implemented React Query hooks for Issue data management
- Added IssueCard component with drag-and-drop support using @dnd-kit
- Created KanbanColumn component with droppable zones
- Built CreateIssueDialog with form validation using zod
- Implemented Kanban page at /projects/[id]/kanban with DnD status changes
- Added missing UI components (textarea, select, skeleton)
- Enhanced API client with helper methods (get, post, put, patch, delete)
- Installed dependencies: @dnd-kit/core, @dnd-kit/sortable, @dnd-kit/utilities, @radix-ui/react-select, sonner
- Fixed SignalR ConnectionManager TypeScript error
- Preserved legacy KanbanBoard component for backward compatibility

Features:
- Drag and drop issues between Backlog, Todo, InProgress, and Done columns
- Real-time status updates via API
- Issue creation with type (Story, Task, Bug, Epic) and priority
- Visual feedback with priority colors and type icons
- Toast notifications for user actions

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

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

lib/api/client.ts

@@ -133,3 +133,31 @@ apiClient.interceptors.response.use(
     return Promise.reject(error);
   }
 );
+
+// API helper functions
+export const api = {
+  get: async <T>(url: string, config?: any): Promise<T> => {
+    const response = await apiClient.get(url, config);
+    return response.data;
+  },
+
+  post: async <T>(url: string, data?: any, config?: any): Promise<T> => {
+    const response = await apiClient.post(url, data, config);
+    return response.data;
+  },
+
+  put: async <T>(url: string, data?: any, config?: any): Promise<T> => {
+    const response = await apiClient.put(url, data, config);
+    return response.data;
+  },
+
+  patch: async <T>(url: string, data?: any, config?: any): Promise<T> => {
+    const response = await apiClient.patch(url, data, config);
+    return response.data;
+  },
+
+  delete: async <T>(url: string, config?: any): Promise<T> => {
+    const response = await apiClient.delete(url, config);
+    return response.data;
+  },
+};

lib/api/issues.ts

@@ -0,0 +1,84 @@
+import { api } from './client';
+
+export interface Issue {
+  id: string;
+  projectId: string;
+  title: string;
+  description: string;
+  type: 'Story' | 'Task' | 'Bug' | 'Epic';
+  status: 'Backlog' | 'Todo' | 'InProgress' | 'Done';
+  priority: 'Low' | 'Medium' | 'High' | 'Critical';
+  assigneeId?: string;
+  reporterId: string;
+  createdAt: string;
+  updatedAt?: string;
+}
+
+export interface CreateIssueDto {
+  title: string;
+  description: string;
+  type: string;
+  priority: string;
+}
+
+export interface UpdateIssueDto {
+  title: string;
+  description: string;
+  priority: string;
+}
+
+export interface ChangeStatusDto {
+  status: string;
+}
+
+export interface AssignIssueDto {
+  assigneeId: string | null;
+}
+
+export const issuesApi = {
+  list: async (projectId: string, status?: string): Promise<Issue[]> => {
+    const params = status ? `?status=${status}` : '';
+    return api.get<Issue[]>(`/api/v1/projects/${projectId}/issues${params}`);
+  },
+
+  getById: async (projectId: string, id: string): Promise<Issue> => {
+    return api.get<Issue>(`/api/v1/projects/${projectId}/issues/${id}`);
+  },
+
+  create: async (projectId: string, data: CreateIssueDto): Promise<Issue> => {
+    return api.post<Issue>(`/api/v1/projects/${projectId}/issues`, data);
+  },
+
+  update: async (
+    projectId: string,
+    id: string,
+    data: UpdateIssueDto
+  ): Promise<Issue> => {
+    return api.put<Issue>(`/api/v1/projects/${projectId}/issues/${id}`, data);
+  },
+
+  changeStatus: async (
+    projectId: string,
+    id: string,
+    status: string
+  ): Promise<void> => {
+    return api.put<void>(
+      `/api/v1/projects/${projectId}/issues/${id}/status`,
+      { status }
+    );
+  },
+
+  assign: async (
+    projectId: string,
+    id: string,
+    assigneeId: string | null
+  ): Promise<void> => {
+    return api.put<void>(`/api/v1/projects/${projectId}/issues/${id}/assign`, {
+      assigneeId,
+    });
+  },
+
+  delete: async (projectId: string, id: string): Promise<void> => {
+    return api.delete<void>(`/api/v1/projects/${projectId}/issues/${id}`);
+  },
+};