feat(shell): make Switch-nix/Test-nix/buildImage system-wide

IPA users (e.g. wayne@) don't get Home Manager so the aliases defined in
aliases.nix were invisible to them. Move Switch-nix, Test-nix, and
buildImage into programs.bash in configuration.nix so every user on every
host gets them via /etc/bashrc. Stub out aliases.nix for future per-user
HM-only additions.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

modules/common/aliases.nix

@@ -1,50 +1,7 @@
-{ config, pkgs, lib, vars, ... }:
+_:
 
-let
-  # Flake attribute names are now <platform>-<buildtype> (e.g. proxmox-docker)
-  # and no longer match networking.hostName, since a host's hostname stays
-  # fixed while the platform backing it can change. Each nixosConfiguration
-  # stamps its own active target name into /etc/flake-target at build time.
-  mySwitchCmd = ''
-    sudo nixos-rebuild switch \
-      --no-write-lock-file \
-      --refresh \
-      --flake git+https://${vars.lanDomain}/beatzaplenty/nixos.git#$(cat /etc/flake-target)
-  '';
-  myTestCmd = ''
-    sudo nixos-rebuild test \
-      --no-write-lock-file \
-      --refresh \
-      --flake git+https://${vars.lanDomain}/beatzaplenty/nixos.git#$(cat /etc/flake-target)
-  '';
-
-  # lxc-* hosts pre-seed their SSH host key at build time (see
-  # modules/platforms/lxc.nix) so sops-nix's .sops.yaml recipient matches on
-  # first boot -- without it, secrets permanently fail to decrypt (see that
-  # file's comment for the confirmed failure). That requires --impure plus
-  # NIXOS_HOST_KEYS_DIR pointing at the repo's host-keys/ dir, same pattern
-  # docs/auto-installer.md uses for the installer ISO. A function, not a
-  # shellAlias, since the target name has to interpolate into the middle of
-  # the flake attribute path, not just append after it. Must be run from the
-  # repo root, same as every other host-keys/ command in this repo.
-  buildImageFn = ''
-    buildImage() {
-      if [ -z "$1" ]; then
-        echo "usage: buildImage <flake-target>  (e.g. lxc-docker)" >&2
-        return 1
-      fi
-      NIXOS_HOST_KEYS_DIR="$(pwd)/host-keys" nix build --impure \
-        ".#nixosConfigurations.$1.config.system.build.tarball"
-    }
-  '';
-in
 {
-  programs.bash = {
-    enable = true;
-    shellAliases = {
-      "Switch-nix" = mySwitchCmd;
-      "Test-nix" = myTestCmd;
-    };
-    initExtra = buildImageFn;
-  };
+  # Switch-nix, Test-nix, and buildImage are defined system-wide in
+  # modules/common/configuration.nix so all users (including IPA accounts)
+  # get them. Add any Home-Manager-only per-user shell config here.
 }