Optimizer reliability, clearer sign-in errors

The Optimizer explains itself better after this one. Apply outcomes, failures, and pending changes all report accurately, and sign-in errors got the same treatment.

• Sign-in shows an error when your email is not yet verified.
• Optimizer apply results are classified more clearly, so blocked, unsupported, and verification issues are surfaced accurately.
• Optimizer history and toast messages explain failed changes in a more useful way.
• Pending Optimizer changes show reliably after an apply attempt instead of lingering in a stale state.
• Stale pending changes no longer trap you on the home page when restarting the app.
• Junk Cleaner properly reports the found junk files in the top header.