## What changed
- Add `intersect_effective_permission_profiles` to derive the permissions shared by an authority profile and a requested profile.
- Preserve the more restrictive filesystem access, read denials, protected metadata paths, temporary-directory access, and network policy.
- Canonicalize concrete paths so symlinks cannot expand authority, and fail closed for policy shapes that cannot be intersected safely.
## Testing
Add coverage for workspace intersections, nested carveouts, deny patterns, unsupported policies, temporary-directory restrictions, symlink escapes, and macOS path aliases.
GitOrigin-RevId: a35bdc47e41afad13630f92c032514b300c14a0d