## Why
Restored app-server threads can carry permission profiles that cannot be
represented without loss as legacy sandbox-mode overrides. Sending those
profiles as per-turn overrides can discard their original permission details.
## What changed
- Distinguish restored permission profiles from legacy per-turn sandbox
overrides.
- Preserve restored profiles while routing turns and changing to compatible
working directories.
- Reject `/cd` when a restored profile cannot be represented safely by a
legacy sandbox mode.
## Testing
- Cover retaining a restored read-only profile across `/cd` without a turn
override.
- Verify that lossy sandbox-mode projections are detected.
GitOrigin-RevId: 6143dca4b83ab4f59bab05f6a59b4fe841c56192