fix(scaffold-ui): auto-trigger SIWX sign on auth view open

[ibruno]

Description

This PR fixes an extra step in the SIWX auth flow by automatically triggering the signature request as soon as the SIWXSignMessage view opens.

Before:

• User connected wallet
• User landed on SIWX sign screen
• User had to click Sign

After:

• User connects wallet
• SIWX signature request opens automatically (no extra click required)

Additional details:

• Keeps the Sign button as a fallback path.
• Adds a guard to avoid duplicate sign requests if auto-trigger and manual trigger overlap.

Validation:

• pnpm build
• pnpm --filter @reown/appkit-scaffold-ui exec vitest run test/views/w3m-siwx-sign-message-view.test.ts

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

N/A

Showcase (Optional)

N/A (behavioral UX improvement; no visual UI redesign)

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: bdf154a

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

This PR includes changesets to release 26 packages

Name	Type
@reown/appkit-scaffold-ui	Patch
@reown/appkit-adapter-ethers	Patch
@reown/appkit-adapter-ethers5	Patch
@reown/appkit-adapter-wagmi	Patch
@reown/appkit	Patch
@reown/appkit-cdn	Patch
@reown/appkit-adapter-bitcoin	Patch
@reown/appkit-adapter-solana	Patch
@reown/appkit-adapter-ton	Patch
@reown/appkit-adapter-tron	Patch
@reown/appkit-universal-connector	Patch
@reown/appkit-experimental	Patch
@reown/appkit-testing	Patch
@reown/appkit-common	Patch
@reown/appkit-ui	Patch
@reown/appkit-controllers	Patch
@reown/appkit-core	Patch
@reown/appkit-utils	Patch
@reown/appkit-polyfills	Patch
@reown/appkit-wallet	Patch
@reown/appkit-siwe	Patch
@reown/appkit-siwx	Patch
@reown/appkit-wallet-button	Patch
@reown/appkit-cli	Patch
@reown/appkit-pay	Patch
@reown/appkit-codemod	Patch

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[github-actions]

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[ibruno]

I have read the CTA Document and I hereby sign the CTA