Each node now gets three NetworkManager wifi connections via a new
wifi role: dotnetwork (home), dotmobile (phone hotspot, for field
troubleshooting), and a host-specific deployed-location network.
Credentials live in a new per-repo ansible-vault (group and host
scoped), matching the pattern already used in dotnetwork.
Also updates the README's Pi imaging instructions from Bookworm to
Trixie, matching what the nodes actually run.
Co-Authored-By: Claude Sonnet 5 <[email protected]>
