Add star feature to save important questions

[KamathAnjali]

✨ Feature: Starred Questions on Leetcode Patterns Page

🔧 What’s Added

• ⭐ Star Toggle per Question

  • Each question now has a clickable star icon
  • Clicking the star toggles its active state with a glow animation

• 📌 Persistence via Local Storage

  • Starred questions are saved to the browser’s local storage
  • Starred state persists across page reloads

• 📋 “View Starred Questions” Button

  • Filters the list to only show starred problems
  • Useful for revisiting important or tricky questions

• 🔔 Toast Notifications

  • Displays a brief message when a question is starred or unstarred
  • Enhances UX with immediate feedback

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✅ Why This Is Useful

• Helps users bookmark and track problems they want to revisit
• Maintains context across sessions without needing login or backend storage