Move ExpandPath function and path-related utilities from internal/config to internal/storage where they belong.
Files updated:
- internal/worker/config.go: use storage.ExpandPath
- internal/network/ssh.go: use storage.ExpandPath
- cmd/data_manager/data_manager_config.go: use storage.ExpandPath
- internal/api/server_config.go: use storage.ExpandPath
internal/storage/paths.go already contained the canonical implementation.
Result: Path utilities now live in storage layer, config package focuses on configuration structs.