Codex caught an edge case in the authorized_keys removal logic:
**Problem:**
When authorized_keys contains ONLY pulse-managed keys, `grep -vF` returns
exit code 1 (no lines matched the inverse filter). The previous code only
executed the rewrite on exit 0, leaving managed keys in place when they
should have been removed.
**Solution:**
- Capture grep exit code explicitly
- Treat both exit 0 (lines remain) and exit 1 (all removed) as success
- Only treat exit codes > 1 as actual errors
- Properly handles the "remove all keys" scenario
This ensures complete removal works even when the file contains nothing
but Pulse-managed entries.
Addresses #123
8d6ab4113d