fix: set quote token amount to zero when source token is empty in swap UI

[Nithishvb]

Description

This PR sets the quote token amount to zero when the source token is empty in the swap UI. This change improves clarity and prevents confusion for users.

Type of change

• Chore (non-breaking change that addresses non-functional tasks, maintenance, or code quality improvements)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Associated Issues

For Linear issues: Closes APKT-xxx
For GH issues: closes #...

Showcase (Optional)

Checklist

• Code in this PR is covered by automated tests (Unit tests, E2E tests)
• My changes generate no new warnings
• I have reviewed my own code
• I have filled out all required sections
• I have tested my changes on the preview link
• Approver of this PR confirms that the changes are tested on the preview link

[changeset-bot]

🦋 Changeset detected

Latest commit: 70defda

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 14 packages

Name	Type
@reown/appkit-core	Patch
@reown/appkit-adapter-bitcoin	Patch
@reown/appkit-adapter-ethers	Patch
@reown/appkit-adapter-ethers5	Patch
@reown/appkit-adapter-solana	Patch
@reown/appkit-adapter-wagmi	Patch
@reown/appkit	Patch
@reown/appkit-utils	Patch
@reown/appkit-scaffold-ui	Patch
@reown/appkit-siwe	Patch
@reown/appkit-siwx	Patch
@reown/appkit-wallet-button	Patch
@reown/appkit-experimental	Patch
@reown/appkit-cdn	Patch

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[arein]

THANK YOU! can you please add some tests?

[Nithishvb]

Hey @arein, thanks for the review! I have added a test case for the fix.