feat: report the node kernel's modules and build configuration

A Proxmox node runs its own kernel under every guest, which makes it the host
where a kernel CVE's preconditions matter most. ProxmoxDriver mixes in
KernelFactsMixin from napalm-device-types and supplies only the transport,
the existing exec path.

Requires napalm-device-types 2.1.0.

tests/test_kernel_facts.py

@@ -0,0 +1,46 @@
+"""`get_kernel_facts`: what the node's kernel has built and loaded.
+
+A Proxmox node runs its own kernel under every guest, which makes it the host
+where a kernel CVE's preconditions matter most. The command and its parse are
+napalm-device-types'; the driver only carries the command over its exec path.
+"""
+
+from __future__ import annotations
+
+import base64
+import gzip
+from unittest.mock import patch
+
+import pytest
+
+from napalm_device_types import KernelFactsMixin
+from napalm_device_types.kernel import KERNEL_FACTS_COMMAND
+from napalm_proxmox.driver import ProxmoxDriver
+
+REPORT = (
+    "[release]\n6.8.12-4-pve\n[loaded]\nkvm_intel\n[builtin]\nkernel/net/ipv4/tcp_cubic.ko\n"
+    "[available]\nkernel/net/tipc/tipc.ko\n[config]\nCONFIG_TIPC=m\n"
+)
+WIRE = "KFACTS_BEGIN\n" + base64.encodebytes(gzip.compress(REPORT.encode())).decode() + "KFACTS_END"
+
+
+def test_the_driver_declares_the_contract():
+    assert issubclass(ProxmoxDriver, KernelFactsMixin)
+
+
+def test_it_runs_the_shared_command(driver):
+    with patch.object(driver, "_exec_ssh_command", return_value=WIRE) as exec_:
+        facts = driver.get_kernel_facts()
+
+    exec_.assert_called_once_with(KERNEL_FACTS_COMMAND)
+    assert facts["release"] == "6.8.12-4-pve"
+    assert facts["loaded"] == ["kvm_intel"]
+    assert facts["builtin"] == ["tcp_cubic"]
+    assert facts["available"] == ["tipc"]
+    assert facts["config"] == {"CONFIG_TIPC": "m"}
+
+
+def test_output_without_a_report_raises(driver):
+    with patch.object(driver, "_exec_ssh_command", return_value=""):
+        with pytest.raises(ValueError):
+            driver.get_kernel_facts()