feat: Implement Threat Analytics Dashboard and Backend Rate Limiting (#172)

[punithkumar-060308]

…(#172)

Summary

Implemented the Threat Analytics Dashboard and backend rate limiting for Issue #172.

Changes

• Added localStorage-based scan history
• Implemented Safe vs Threat chart using Chart.js
• Added Threat Types bar chart
• Added Recent Scans table
• Added dashboard statistics
• Added robust history parsing
• Implemented Express rate limiting for the /check endpoint
• Updated README to reflect the completed feature

Testing

• Verified URL scanning works correctly
• Verified scan history persists after page refresh
• Verified dashboard charts and recent scans table update correctly
• Verified backend starts successfully and rate limiting is applied

Closes #172

[punithkumar-060308]

Hi @Mrinalray,

This PR is submitted as part of ECSOC. Could you please add the ECSOC26 label if required?

Thank you!