Fix build errors and TypeScript issues

- Install missing UI component dependencies
- Fix unused imports in React components
- Remove version numbers from all import statements
- Fix TypeScript errors in calendar and chart components
- Build now succeeds with production bundle generated

App.tsx

@@ -1,4 +1,4 @@
-import React, { useState } from 'react';
+import { useState } from 'react';
 import { AppProvider } from './contexts/AppContext';
 import { KanbanBoard } from './components/KanbanBoard';
 import { ProductBacklog } from './components/ProductBacklog';