f1a98be8de
FW-02: atomic_dump_yaml now calls _atomic_dump_yaml_check_nfs() which detects NFS/CIFS/SSHFS mounts and warns that flock is unreliable. Long-term fix (SQLite WAL) documented in FUTURE_WORKS.md. FW-11: pyyaml added to requirements.txt and installed in .venv, so both paho-mqtt and yaml are available in a single interpreter. Eliminates the system-python3-vs-venv split for monitor --subscribe.