* Added backoff and liveness probes for better management
* Switched IPC to a simple text based system
* Lookups don't directly touch the agent now
* Use the database as a source of truth
Adds a new Nix flake output `headplane-nixos-docs` which generates a
Markdown page with all NixOS `services.headplane.settings.*` options.
Replaces existing handwritten options documentation.