uplift(beta): fix(ui): use selected account for manage folders (#11152)

[wmontwe]

Uplift #11152 to beta

[thunderbird-botmobile]

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[Approval Request]
Original Issue/Pull request: #11175 / #11177
Regression caused by (issue #): n/a
User impact if declined: When selecting an account the wrong account is opened when manage folders is selected
Testing completed (on daily, beta, etc.): daily
Introduces or modifies localizable strings (yes/no): no
Skips a database migration (yes/no): no
Risk to taking this patch (and alternatives if risky): Low as it always fallbacks to a valid account

[github-actions]

✅ Validation Passed: All report and feature-flag labels are correctly set.