Do work to add Content Security Policy (CSP) to frontend

[jupiter007]

CSP is important to guard against various security threats such as cross-site scripting. Do some research to see whether it makes sense to add it to frontend code, and how best to implement.

Tasks:

• Define CSP
  -- Define requirements, like default-src, script-src
• Update next.config.js file to include the CSP headers
• Test your implementation, and use tools like CSP Evaluator.