v0.3.4

feat(tmp): ephemeral sandboxed environments for proto

Adds 'proto tmp' to spin up bwrap sandboxes (default) or real rootfs
(--rootfs) with an isolated private /home and /tmp over a read-only host
root, own uid/gid mapping, and all host tools visible. Registry at
PROTO_TMP_HOME/XDG_CONFIG_HOME. Normal exit prompts save/discard; abnormal
exit (kill/crash) auto-zips the overlay, marks it stopped for 24h recovery
via restore; cleanup purges all inactive; --local runs an ephemeral
/tmp/proto/<hash6> sandbox that always discards.