feat: add motivational quote

[faizaanjum7]

Related Issue

Closes #94

Summary

Added a motivational quote widget to create a more engaging and positive study experience for users, the widget displays a daily rotating productivity quote below the calendar heading

Changes Made

• Added a motivational quote widget below the calendar title
• Added a set of productivity/study-related quotes
• Implemented date-seeded random quote logic to show one stable quote per day
• Styled the quote widget to match the existing UI

Testing

• Tested locally in browser
• Verified quote change
• Verified same quote persists across page refreshes during the same day

Screenshots

Checklist

• Code follows project style
• Tested locally
• No unrelated changes included
• Documentation updated (if applicable)