Import: report a job Studio stopped following as outcome unknown, not failed #1939

Problem

waitForJob (src/integrations/api/instance/database/getJob.ts) follows an import's Harper job until it is COMPLETE or ERROR. It can stop following in two other ways, and both are reported as a plain failure even though the load may still be running on the server:

• Five get_job polls fail in a row: it rethrows the last poll's error (if (consecutiveFailures >= 5) throw err;). For example, the instance stops answering for a few seconds, or a gateway returns 502s.
• The 10-minute deadline passes while the job is still running: it throws Timed out waiting for the import job to finish. Check the table in a few minutes.

Either way the import UI shows it as a failed import. A user who retries then loads the same data a second time. For a CSV with no primary-key column, Harper generates new ids, so the retry duplicates rows. waitForJob's own comment already names this risk for observer failures: a load Harper completed should never be reported as a failure, because that "invites a duplicating retry".

Ask

When following stops without a terminal job status, report it as outcome unknown, the same way #1897 does for writes with no verdict. Say the import may still be running or may have finished, point to the Jobs tab and the table, and don't suggest retrying. #1938 already refreshes the table on these outcomes.

Raised by the cross-model review of #1938 (an import refreshes the table it wrote to); left out of that PR as pre-existing.