fix(syncRef): avoid infinite sync

[chaii3]

#fixes #3289

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⚠️ Slowing down new functions

Warning: Slowing down new functions

As the VueUse audience continues to grow, we have been inundated with an overwhelming number of feature requests and pull requests. As a result, maintaining the project has become increasingly challenging and has stretched our capacity to its limits. As such, in the near future, we may need to slow down our acceptance of new features and prioritize the stability and quality of existing functions. Please note that new features for VueUse may not be accepted at this time. If you have any new ideas, we suggest that you first incorporate them into your own codebase, iterate on them to suit your needs, and assess their generalizability. If you strongly believe that your ideas are beneficial to the community, you may submit a pull request along with your use cases, and we would be happy to review and discuss them. Thank you for your understanding.

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Description

Additional context

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🤖 Generated by Copilot at 76294db

This pull request improves the syncRef function and its test case. It uses pausableWatch to avoid circular updates when syncing refs with mutual convertors, and it tests more realistic scenarios for the convertor functions. It also refactors the syncRef code for readability and consistency.

🤖 Generated by Copilot at 76294db

• Use pausableWatch instead of watch to sync refs with mutual convertors and avoid circular updates (link, link, link, link, link, link)
• Modify the test case for syncRef with mutual convertors in packages/shared/syncRef/index.test.ts to use different initial values and transform functions, and assert the expected values after sync and change (link, link)
• Add a comment to document the options parameter for the syncRef function in packages/shared/syncRef/index.ts (link)

[nothing-sy]

If the flush paramter of options is 'post', dose it work properly?