Warn users when SQLite diagnostic log writes fail

[copyberry]

Warn users when SQLite diagnostic log writes fail

Why

Failed SQLite writes leave diagnostic logs incomplete. Notify users before they close Codex so they can submit logs or run codex doctor.

What changed

• Add a best-effort warning on the first log write failure in standalone and in-process app servers, while continuing to retain failure diagnostics in memory.
• Handle failures that occurred before the in-process warning reporter was attached.
• Tailor the warning's guidance to whether submitting logs is enabled.

Testing

Add coverage for warning deduplication, both guidance variants, retained diagnostics after the notification sender is dropped, and SQLite flush failures before and after reporter attachment. Extend log upload integration coverage and add a TUI warnings snapshot.

[github-actions]

Thank you for your submission, we really appreciate it. Like many open-source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution. You can sign the CLA by just posting a Pull Request Comment same as the below format.

---

I have read the CLA Document and I hereby sign the CLA

---

_{You can retrigger this bot by commenting recheck in this Pull Request. Posted by the CLA Assistant Lite bot.}