feat: Cancel Account Sync Option

[sub-hub]

PR Checklist

• Required Checks
  • Have you added type definitions?
  • Have you tested your changes?
  • Have you checked that it won't break any existing features?
• If your PR uses models¹, check the following:
  • Have you checked if it works normally in all models?
  • Have you checked if it works normally in all web, local, and node-hosted versions? If it doesn't, have you blocked it in those versions?
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  • Have you understood what the code does?
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Summary

Add third option to checkAccountSync page, Cancel Account Sync.

Description

Actually, users can already cancel account sync by selecting Save Current Data to Account and type a random string in the confirm input.

            const confirm = await alertInput(`to overwrite your data, type "RISUAI"`)
            if(confirm !== "RISUAI"){
                localStorage.setItem('dosync', 'avoid')
                return false
            }

However, this is a very unfriendly way of doing things. Who would risk overwriting their own data just to cancel account sync?

So, I'd really like to see this PR merged. It would be much more intuitive to have a cancel button rather than telling people who don't want the sync to just overwrite and cancel the data.

Footnotes

1. Modifies the behavior of prompting, requesting, or handling responses from AI models. ↩

2. Over 80% of the code is AI generated. ↩

[cubicj]

Verified the account sync decision path. I had also run into this before, and the new cancel option gives account sync users a clear safe path instead of the overwrite-confirm workaround.

Check, tests, and build pass locally.

Approving — thanks for the contribution!