Reapply "remove nix_shell_legacy"

This reverts commit c5001f19fc.

pkgs/clan-cli/clan_cli/vms/run.py

@@ -19,7 +19,7 @@ from clan_cli.dirs import module_root, user_cache_dir, vm_state_dir
 from clan_cli.errors import ClanCmdError, ClanError
 from clan_cli.facts.generate import generate_facts
 from clan_cli.machines.machines import Machine
-from clan_cli.nix import nix_shell_legacy
+from clan_cli.nix import nix_shell
 from clan_cli.qemu.qga import QgaSession
 from clan_cli.qemu.qmp import QEMUMonitorProtocol
 
@@ -96,8 +96,8 @@ def prepare_disk(
     file_name: str = "disk.img",
 ) -> Path:
     disk_img = directory / file_name
-    cmd = nix_shell_legacy(
-        ["nixpkgs#qemu"],
+    cmd = nix_shell(
+        ["qemu"],
         [
             "qemu-img",
             "create",
@@ -127,7 +127,7 @@ def start_vm(
 ) -> Iterator[subprocess.Popen]:
     env = os.environ.copy()
     env.update(extra_env)
-    cmd = nix_shell_legacy(packages, args)
+    cmd = nix_shell(packages, args)
     machine.debug(f"Starting VM with command: {cmd}")
 
     with subprocess.Popen(
@@ -280,11 +280,11 @@ def spawn_vm(
             interactive=stdin is None,
         )
 
-        packages = ["nixpkgs#qemu"]
+        packages = ["qemu"]
 
         extra_env = {}
         if vm.graphics and not vm.waypipe.enable:
-            packages.append("nixpkgs#virt-viewer")
+            packages.append("virt-viewer")
             remote_viewer_mimetypes = module_root() / "vms" / "mimetypes"
             extra_env["XDG_DATA_DIRS"] = (
                 f"{remote_viewer_mimetypes}:{os.environ.get('XDG_DATA_DIRS', '')}"