Enhancement: disable compare button during async requests

[Plansha]

Description

This PR improves the Friend Comparison form by preventing duplicate async submissions during ongoing API requests.

Changes Made

• Reused existing loading state to prevent repeated submissions
• Disabled compare button during async requests
• Added loading feedback (Comparing...)
• Added guard clause to prevent duplicate API calls

Benefits

• Prevents duplicate requests
• Improves UX consistency
• Avoids accidental repeated actions during async processing

Fixes #2238

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[github-actions]

GSSoC Label Checklist 🏷️

@Priyanshu-byte-coder — please apply the appropriate labels before merging:

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• level:beginner — 20 pts
• level:intermediate — 35 pts
• level:advanced — 55 pts
• level:critical — 80 pts

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• quality:exceptional — ×1.5 multiplier

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[Plansha]

@Priyanshu-byte-coder , Implemented loading-state protection for the Friend Comparison form by reusing the existing loading state.

Changes

• Disabled compare button during async requests
• Added duplicate submission guard clause
• Added loading feedback (Comparing...)

Tested locally and verified that repeated clicks no longer trigger multiple requests.

[Priyanshu-byte-coder]

Hi! This PR has merge conflicts with the main branch. Could you please rebase or merge main into your branch to resolve them? We'd love to get this merged! 🚀

git fetch upstream
git rebase upstream/main
# resolve any conflicts
git push --force-with-lease

If you're no longer working on this, let us know and we can close it. Thanks!

[Priyanshu-byte-coder]

This PR has merge conflicts with the main branch. Please rebase your branch on latest main and resolve the conflicts so it can be reviewed and merged.