## Summary
- cap feedback log uploads to at most eight threads before SQLite log
aggregation and rollout attachment resolution
- keep the root session included while bounding descendant fanout during
`/feedback` uploads
## Why
Very large sessions can accumulate large spawned-thread subtrees.
Feedback uploads currently walk the entire subtree and then read each
resolved rollout into memory, which can blow up when one session has
hundreds of descendants.
## Validation
- ran `just fmt`
- did not run tests or Clippy per request; CI will cover validation