feat: report where an update comes from and whether it is a security fix, refresh the index, read the host status

For netOrk MVP 5, on napalm-device-types 2.3.0:

- get_available_updates reads `apt list --upgradable` over the exec path
  (APT_UPGRADABLE_COMMAND), so each update carries its suite and security
  status; the APT API, which names only "Debian"/"Proxmox", is the fallback
  with security unknown. It raises when neither answers instead of returning
  [] -- it used to swallow every error.
- refresh_available_updates(): POST nodes/{n}/apt/update.
- HostStatusMixin over the exec path (reboot required, self-patching).

tests/test_updates.py

@@ -0,0 +1,120 @@
+"""Pending updates on a Proxmox node: from where, whether they are security fixes,
+and whether the node needs a reboot.
+
+The node's APT API names only an Origin ("Debian", "Proxmox"), the same for the
+main and the security archive. ``apt list --upgradable`` over the exec path
+names the suite (``trixie-security``), so that is read first; the API remains
+the fallback, with the security status left unknown. A reader that cannot read
+raises: an empty list would tell netOrk that nothing is pending.
+"""
+
+from __future__ import annotations
+
+from unittest.mock import MagicMock, patch
+
+import pytest
+from napalm_device_types import HostStatusMixin
+from napalm_device_types.host_status import HOST_STATUS_COMMAND
+from napalm_device_types.package_updates import APT_UPGRADABLE_COMMAND
+
+from napalm_proxmox.driver import ProxmoxDriver
+
+APT = (
+    "libssl3t64/stable-security 3.5.1-1+deb13u2 amd64 [upgradable from: 3.5.1-1+deb13u1]\n"
+    "ceph-common/stable 20.2.4-pve5 amd64 [upgradable from: 20.2.4-pve4]\n"
+)
+API_ENTRY = {
+    "Package": "librados2",
+    "OldVersion": "20.2.4-pve4",
+    "Version": "20.2.4-pve5",
+    "Origin": "Proxmox",
+}
+
+
+def _api_updates(driver, entries=None, error=None):
+    api = MagicMock()
+    getter = api.nodes.return_value.apt.update.get
+    if error:
+        getter.side_effect = error
+    else:
+        getter.return_value = entries or []
+    driver._api = api
+    return api
+
+
+class TestAvailableUpdates:
+    def test_apt_over_the_exec_path_names_the_suite(self, driver):
+        with patch.object(driver, "_exec_ssh_command", return_value=APT + "__APT_RC=0\n") as exec_:
+            updates = {u["name"]: u for u in driver.get_available_updates()}
+
+        exec_.assert_called_once_with(APT_UPGRADABLE_COMMAND)
+        assert updates["libssl3t64"]["security"] is True
+        assert updates["ceph-common"]["security"] is False
+        assert updates["ceph-common"]["origin"] == "stable"
+
+    def test_the_api_is_the_fallback_with_security_unknown(self, driver):
+        _api_updates(driver, [API_ENTRY])
+        with patch.object(driver, "_exec_ssh_command", return_value=""):
+            updates = driver.get_available_updates()
+
+        assert updates == [
+            {
+                "name": "librados2",
+                "current_version": "20.2.4-pve4",
+                "new_version": "20.2.4-pve5",
+                "origin": "Proxmox",
+                "security": None,
+            }
+        ]
+
+    def test_a_failed_apt_falls_back_too(self, driver):
+        _api_updates(driver, [API_ENTRY])
+        with patch.object(driver, "_exec_ssh_command", return_value="E: lock\n__APT_RC=100\n"):
+            assert [u["name"] for u in driver.get_available_updates()] == ["librados2"]
+
+    def test_nothing_readable_raises_instead_of_reporting_nothing(self, driver):
+        _api_updates(driver, error=RuntimeError("API timeout"))
+        with patch.object(driver, "_exec_ssh_command", return_value=""):
+            with pytest.raises(RuntimeError):
+                driver.get_available_updates()
+
+    def test_nothing_pending_is_an_empty_list(self, driver):
+        with patch.object(driver, "_exec_ssh_command", return_value="__APT_RC=0\n"):
+            assert driver.get_available_updates() == []
+
+
+class TestRefresh:
+    def test_the_node_refreshes_its_index_through_the_api(self, driver):
+        api = _api_updates(driver)
+        api.nodes.return_value.apt.update.post.return_value = "UPID:pve1:0001"
+
+        result = driver.refresh_available_updates()
+
+        assert result["success"] is True
+        api.nodes.return_value.apt.update.post.assert_called_once()
+
+    def test_a_refused_refresh_says_why(self, driver):
+        api = _api_updates(driver)
+        api.nodes.return_value.apt.update.post.side_effect = RuntimeError(
+            "403 Permission check failed"
+        )
+
+        result = driver.refresh_available_updates()
+
+        assert result == {"success": False, "output": "403 Permission check failed"}
+
+
+class TestHostStatus:
+    def test_the_node_is_read_over_the_exec_path(self, driver):
+        report = (
+            "HSTAT_BEGIN\n[kernel]\n7.0.14-19-pve\n[modules]\n7.0.14-19-pve\n7.0.2-6-pve\n"
+            "[timers]\napt-daily-upgrade.timer enabled\nHSTAT_END\n"
+        )
+        with patch.object(driver, "_exec_ssh_command", return_value=report) as exec_:
+            status = driver.get_host_status()
+
+        exec_.assert_called_once_with(HOST_STATUS_COMMAND)
+        assert status["reboot_required"] is False
+
+    def test_the_driver_declares_the_contract(self):
+        assert issubclass(ProxmoxDriver, HostStatusMixin)