Investigate and fix this error
Investigate and fix this error

Outcome
Fixed the attachment upload HTTP 500: files over 2 GiB overflowed the 32-bit task_attachments.size_bytes (cap is 5 GiB). Migration widens it to BIGINT, with a regression test. Quick gate green; PR #6207 queued in the merge lane.
Artifacts
Attachments
Activity
- Run
- Runner started
- Awaiting response
- Awaiting response
- Runner resumed
- Runner ended (done)