Implement guest tool installation and management system

- Added `guest_tools.py` for standalone tool installer functionality.
- Introduced `ToolJobStore` in `tool_store.py` to manage per-VM tool job records.
- Created `ToolService` in `tools.py` for background installation workers using the guest execution channel.
- Enhanced `LifecycleService` in `lifecycle.py` to support tool installation queuing and preparation.
- Updated `guest_exec.py` to handle connection shutdown gracefully.
- Added validation and normalization functions for tool specifications.
- Implemented logging and error handling for tool installation processes.
- Ensured compatibility with Ubuntu 22.04 and ARM64/x86_64 architectures.

uvm/config.py

@@ -3,6 +3,7 @@
 from __future__ import annotations
 
 import os
+import math
 from dataclasses import dataclass, field
 from ipaddress import IPv4Address, IPv4Network
 from pathlib import Path
@@ -46,6 +47,9 @@ class Settings:
     api_timeout_s: float = 2.0
     api_socket_timeout_s: float = 5.0
     terminate_timeout_s: float = 5.0
+    tool_workers: int = 2
+    tool_ready_timeout_s: float = 120.0
+    tool_install_timeout_s: float = 1200.0
 
     def __post_init__(self) -> None:
         architecture = self.architecture.lower()
@@ -54,6 +58,13 @@ class Settings:
             raise ConfigurationError(f"unsupported host architecture: {self.architecture}")
         object.__setattr__(self, "architecture", architecture)
 
+        if type(self.tool_workers) is not int or not 1 <= self.tool_workers <= 8:
+            raise ConfigurationError("tool_workers must be an integer between 1 and 8")
+        for name in ("tool_ready_timeout_s", "tool_install_timeout_s"):
+            value = getattr(self, name)
+            if type(value) not in (int, float) or not math.isfinite(value) or not 0 < value <= 3600:
+                raise ConfigurationError(f"{name} must be finite, greater than zero, and at most 3600 seconds")
+
         # Resolve defaults at construction time, while preserving individual URL overrides.
         asset_base = f"{DEFAULT_GUEST_ASSETS_URL}/{architecture}"
         if not self.kernel_url: