refactor: reorganize, add package (opencode, osgrep, beads), add ai agent shell

modules/nixos/hosts/dev-vm.nix

@@ -1,51 +0,0 @@
-{ lib, pkgs, ... }: {
-  networking.hostName = "dev-vm";
-  # Set the baseline NixOS release used for stateful data; bump on rebuilds.
-  system.stateVersion = lib.mkDefault "24.05";
-
-  # Boot loader configuration for VM
-  boot.loader.grub.enable = lib.mkDefault true;
-  boot.loader.grub.device = lib.mkDefault "/dev/vda";
-
-  # Root filesystem configuration for VM
-  fileSystems."/" = lib.mkDefault {
-    device = "/dev/vda1";
-    fsType = "ext4";
-  };
-
-  environment.systemPackages = with pkgs; [
-    # Core utilities
-    coreutils
-    ast-grep
-    ripgrep
-    bat
-    tree
-    zip
-    unzip
-    jq
-    psmisc # provides killall and friends
-    gh
-    tree-sitter
-
-    # System monitoring & debugging tools
-    htop # Process viewer
-    iotop # I/O monitoring
-    lsof # List open files
-    strace # System call tracing
-    ltrace # Library call tracing
-    gdb # GNU debugger
-    tcpdump # Network packet analyzer
-    ncdu # Disk usage analyzer
-  ];
-
-  services.qemuGuest.enable = true;
-
-  services.openssh.openFirewall = false;
-
-  networking.firewall = {
-    allowedTCPPorts = [ ];
-    interfaces."tailscale0".allowedTCPPorts = [ 22 ];
-  };
-
-  imports = [ ../virtualization.nix ];
-}