Add support for Code 360 platform

• Updated manifest.json to include Code 360 URLs and data resources.
• Modified popup.html to add a checkbox for Code 360 platform selection.
• Enhanced popup.js to handle problem counts and data fetching for Code 360.
• Implemented a new scraper for Code 360 to fetch problem data and save it in JSON format.
• Updated scrape.py to include Code 360 in the list of scrapers and handle its specific logic.
• Improved styles.css to enhance the UI for platform tabs, including scroll buttons and styling adjustments.
• Other small UI and performance Issues fixed