Attaching the overlay

The store is <overlay>/projects/<project name>/memory, where the name is the [project] name
in this repository's stayfixed.toml, and attach derives it: the overlay root comes from the
machine configuration, not from what is typed here.

1. Run stayfixed attach --check first. It reports whether this machine already
   binds this checkout (bound or unbound), and which allow rules would be added. It
   writes nothing.
2. Run stayfixed attach; it merges the rules, installs the overlay's hooks, skills and agents as
   this checkout's local plugin, points the harness's memory at the overlay's notes where
   memory.mode is overlay (nowhere otherwise), all in the main checkout, which every worktree
   reads, and prints one screen: the binding with the
   project it is recorded under, the hook entries, skills and agents added or removed since the last
   attach, and the allow rules added. Relay that screen to the user, and a line saying the binding
   moved to another project above all. If it exits 1 because a claude plugin call did not succeed,
   say so; running it again completes it. It asks for no confirmation: the overlay is the owner's
   own. On Codex only the overlay's rules arrive, copied into .codex/rules/; its hooks, skills and
   agents reach Claude Code alone, so say that rather than tell a Codex user they were delivered.
3. If the report or the run names two remotes -- this checkout's origin is not the one the
   binding or the overlay records -- relay that line. It refuses nothing: the binding is an id
   this machine keeps, never the remote. Never print or relay more of the binding id than the
   eight characters the command prints.
4. stayfixed detach withdraws the overlay's plugin and removes the merged rules, the Codex rule
   files, the memory pointer and the local ledger, and leaves the overlay's project record
   untouched.
   Relay what it removed. If it exits 1 because the settings file still names the plugin, relay
   that line; running it again once claude plugin runs finishes it.
5. Personal rules, notes and permissions live in the overlay and nowhere else. Never copy one
   into the project repository, and never widen a permission on the user's behalf.