- Replace 'nohup ... server & disown' with portable Python 'Popen(..., start_new_session=True)' in lib.sh shim generator
- Isolate headless herdr server in its own SID/PGID to protect against parent process-group signal broadcast (SIGTERM/SIGINT)
- Add regression test test_h26_daemon_spawn_uses_process_group_detachment to verify child PGID detachment (Closes#3 Item 1)
- Add test_r2 and test_r3 for bare-kind fallback restriction and R-1 exact-match enforcement
- Add test_h24 and test_h25 for idle-pane reuse and env_flags preservation