Fix duplicate updatePieChart function causing signup and login errors

[Codectrix-0]

Problem

The browser console shows these errors:

• Uncaught SyntaxError: Identifier 'updatePieChart' has already been declared
• Uncaught ReferenceError: signup is not defined
• Uncaught ReferenceError: login is not defined

Cause

There are multiple declarations of updatePieChart() in script.js, which stops JavaScript execution and prevents authentication functions from loading.

Expected Behavior

• Only one updatePieChart() function should exist.
• Signup button should work.
• Login button should work.
• No console errors.

Tasks

• Find duplicate updatePieChart() declarations.
• Remove the extra declaration.
• Verify signup works.
• Verify login works.
• Check browser console for zero errors.