[WIP] Security Agent

[Copilot]

• Create security audit report for the repository
• Fix CORS configuration in the bank project API
• Improve input validation in the bank project API
• Restrict host permissions in browser extension
• Create security utility module for browser extension
• Update GitHub Actions workflow security
• Add secure API key handling guidelines in documentation
• Update vulnerable dependencies

Fixes #1408.

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[github-actions]

This PR has not seen any action for a while! Closing for now, but it can be reopened at a later date.