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

contexts/AppContext.tsx

@@ -1,4 +1,4 @@
-import React, { createContext, useContext, useState, ReactNode } from 'react';
+import { createContext, useContext, useState, ReactNode } from 'react';
 import { Task, UserStory, Sprint } from '../types';
 
 interface AppContextType {