Add loading and disabled states for authentication actions

[Rishabhjain610]

Description

Added loading indicators and disabled states for authentication actions to prevent duplicate submissions and improve user experience.

Related Issue

Closes #407

Changes Made

• Added loading states for login and signup actions.
• Disabled authentication buttons while requests are pending.
• Prevented duplicate API requests.
• Preserved existing authentication flows.

Checklist

• Tested locally
• No regressions
• Linked the related issue

[vercel]

@Rishabhjain610 is attempting to deploy a commit to the santanu-atta03's projects Team on Vercel.

A member of the Team first needs to authorize it.

[github-actions]

Thanks for creating a PR for your Issue! ☺️

We'll review it as soon as possible.
In the meantime, please double-check the file changes and ensure that all commits are accurate.

If there are any unresolved review comments, feel free to resolve them. 🙌🏼