Add _CapturingSyncLogRepository and two tests (IMAP + JMAP) that assert a failed sync cycle produces an error entry in the sync log. Also replace .ignore() in the catch blocks with a proper try-catch so the sync log write is genuinely attempted and any secondary failure is logged to stdout rather than silently dropped. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>