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/zsh.nix

@@ -1,7 +1,8 @@
-{ config
-, lib
-, pkgs
-, ...
+{
+  config,
+  lib,
+  pkgs,
+  ...
 }:
 {
   config = {
@@ -18,6 +19,8 @@
         eval "$(direnv hook zsh)"
         export GPG_TTY=$(tty)
         export EDITOR="nvim -n -c 'set noswapfile nobackup nowritebackup'"
+        export SSH_AUTH_SOCK=$(gpgconf --list-dirs agent-ssh-socket)
+
       '';
 
       shellAliases = {