fix(query-db-collection): forward structuralSharing to QueryObserver

[kisk23]

🎯 Changes

• Forward the structuralSharing option from QueryCollectionConfig to the underlying QueryObserver.
• Removes the hard-coded default and allows consumers to control TanStack Query structural sharing behavior.
• Adds a regression test verifying the option is forwarded correctly.

✅ Checklist

• [✓ ] I have followed the steps in the Contributing guide.
• [✓ ] I have tested this code locally with pnpm test:pr.

🚀 Release Impact

• [ ✓] This change affects published code, and I have generated a changeset.
• This change is docs/CI/dev-only (no release).

[changeset-bot]

🦋 Changeset detected

Latest commit: 7434ec1

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

This PR includes changesets to release 1 package

Name	Type
@tanstack/query-db-collection	Patch

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