Add DMS configuration and helper scripts

- Introduced a new `justfile` for managing DMS-related tasks, including a recipe for syncing live DMS configuration.
- Added a `devshell.nix` file to set up a development environment with necessary packages and shell hooks for DMS.
- Updated DMS settings to replace `defaultSettingsFile` with `defaultSeedDir` for improved configuration management.
- Created a new script `sync-seed.sh` to facilitate syncing DMS settings from the live configuration to host-specific directories.
- Enhanced documentation and examples for DMS configuration and usage.

modules/deploy/navi.nix

@@ -116,16 +116,6 @@ in
       "x86_64-linux"
       "aarch64-linux"
     ]) {
-      devShells.default = pkgs.mkShell {
-        packages = [ inputs.navi.packages.${system}.default ];
-        shellHook = ''
-          echo "Navi fleet deploy (from repo root):"
-          echo "  navi apply --on <host>     # build + switch one host"
-          echo "  navi apply-local --node 14900k --sudo   # switch this machine locally (needs root), --node if hostname differs"
-          echo "  navi tui                   # interactive fleet dashboard"
-        '';
-      };
-
       apps = {
         navi = {
           type = "app";