Stop pulse-sensor-proxy service before modifying config.yaml to prevent
races with the running daemon or concurrent CLI commands.
The migration script now:
1. Stops service if running
2. Updates config atomically (temp + rename in same directory)
3. Restarts service if it was running
This achieves complete architectural isolation - ALL config file writers
are now coordinated (either through Phase 2 CLI locking or by ensuring
the service is stopped during modification).
Addresses final Codex review feedback.
rcourtman
879de50131