Seed a new worktree's target without its path crates

scripts/heavy.sh seeds a worktree without a build of its own by APFS-cloning another checkout’s target/<profile>/{deps,build,.fingerprint}. Cargo fingerprints path crates by mtime, so a clone from a checkout that was built later could look fresh and be stale. In one case cargo test -p napdock-app failed with no field 'failure' on type '&ExtensionDevLink' because contracts came from a checkout 34 commits behind.

After cloning, seed_target now deletes every path crate’s entries, using names from cargo metadata --offline. Registry and git crates stay shared. A verified run compiled the path crates and finished in 2m 08s instead of the 20 to 30 minutes of a cold build. AGENTS.md describes the behavior.