chore: update Nix configurations for Nixcloud and common hosts

- Add Nixcloud host configurations including networking, hardware, and system settings
- Refactor existing configurations for clarity and organization
- Remove unused podman configuration from home-manager
- Update SSH agent settings and session variables in Nixbook host

home-manager/home.nix

@@ -126,15 +126,6 @@
       };
     };
 
-    podman = {
-      enable = true;
-      dockerCompat = true; # optional: use docker commands
-      extraPackages = with pkgs; [
-        fuse-overlayfs
-        slirp4netns
-      ];
-    };
-
     vscode = {
       enable = true;
     };