Refactor VM lifecycle management and enhance validation

- Introduced a new method `installed_kernel` in `ImageStore` to handle kernel verification and checksum validation.
- Updated `Installer` to include additional packages: `nftables` and `conntrack`.
- Refined `LifecycleService` to improve error handling and state management during VM creation, starting, stopping, and deletion.
- Enhanced port management with new methods for setting and syncing ports, including validation for port rules.
- Improved error handling in `StateStore` to raise specific `NotFoundError` and `ConflictError` exceptions.
- Updated network management to ensure proper TAP device handling and firewall integration.
- Enhanced API responses in `vms.py` to include policy status for better client-side handling.
- Added validation for VM names and ports in `validation.py` to enforce stricter rules and prevent conflicts.

uvm/system.py

@@ -5,6 +5,7 @@ from __future__ import annotations
 import os
 import shlex
 import subprocess
+import sys
 from collections.abc import Callable, Sequence
 from dataclasses import dataclass
 from pathlib import Path
@@ -47,7 +48,7 @@ class CommandRunner:
                 check=False,
                 text=True,
                 input=input_text,
-                stdout=subprocess.PIPE if capture else None,
+                stdout=subprocess.PIPE if capture else sys.stderr,
                 stderr=subprocess.PIPE if capture else None,
                 timeout=timeout,
             )