feat: report the firmware Netgear offers, not a warning (0.4.0)

The Plus driver looked the newest firmware up in Netgear's download
catalogue and named firmware_update_available itself. It now reports
get_firmware_offer() (napalm-device-types 4.16 FirmwareOfferMixin): what
runs, the newest offered, whether that is newer by Netgear's versioning,
and the download link; netOrk names the warning (netOrk #1111). The Smart
driver's empty get_device_warnings goes too. Requires
napalm-device-types 4.16.0.

napalm_netgear/netgear_plus.py

@@ -26,7 +26,7 @@ import threading
 import time
 from typing import Any
 
-from napalm_device_types import FingerprintRule, SwitchDriver
+from napalm_device_types import FingerprintRule, FirmwareOfferMixin, SwitchDriver
 from napalm.base.exceptions import ConnectionException
 
 # ---------------------------------------------------------------------------
@@ -144,7 +144,7 @@ def _fw_get_latest(model: str) -> str | None:
     return latest
 
 
-class NetgearPlusDriver(SwitchDriver):
+class NetgearPlusDriver(FirmwareOfferMixin, SwitchDriver):
     """HTTP-based NAPALM driver for Netgear Plus Smart Managed switches."""
 
     VENDOR = "Netgear"
@@ -753,50 +753,29 @@ class NetgearPlusDriver(SwitchDriver):
         Returns None to indicate SNMP health monitoring is not supported."""
         return None
 
-    def get_device_warnings(self) -> list:
-        """Check for available firmware updates and return a warning if the
-        device is not running the latest known firmware.
+    def get_firmware_offer(self) -> dict | None:
+        """The firmware running and the newest Netgear offers for this model.
 
-        The latest version is looked up once per 24 hours (per model, per
-        worker process) via lightweight HEAD requests against Netgear's
-        download CDN.  Returns an empty list when the model is unknown or
-        when the check fails.
+        The newest is looked up once per 24 hours (per model, per worker
+        process) with HEAD requests against Netgear's download CDN. None when
+        the model is unknown, a version cannot be read or compared, or the
+        check fails. Whether an older firmware is a warning is the caller's to
+        decide (napalm-device-types ``FirmwareOfferMixin``).
         """
-        warnings: list = []
         try:
             model_name: str = getattr(
                 self._connector.switch_model, "MODEL_NAME", ""
             ) or self._connector.switch_model.__class__.__name__
             current_fw: str = self._get_switch_infos().get("switch_firmware", "")
-
-            if not model_name or not current_fw:
-                return warnings
-
-            latest_fw = _fw_get_latest(model_name)
+            latest_fw = _fw_get_latest(model_name) if model_name and current_fw else None
             if latest_fw is None:
-                return warnings
-
-            try:
-                current_t = _fw_version_tuple(current_fw)
-                latest_t = _fw_version_tuple(latest_fw)
-            except ValueError:
-                return warnings
-
-            if latest_t > current_t:
-                warnings.append(
-                    {
-                        "code": "firmware_update_available",
-                        "meta": {
-                            "download_url": (
-                                f"{_FW_CDN_BASE}/{model_name}"
-                                f"/{model_name}_{latest_fw}.zip"
-                            ),
-                            "latest_version": latest_fw,
-                            "current_version": current_fw,
-                        },
-                    }
-                )
+                return None
+            newer = _fw_version_tuple(latest_fw) > _fw_version_tuple(current_fw)
         except Exception:
-            pass
-
-        return warnings
+            return None
+        return {
+            "current_version": current_fw,
+            "latest_version": latest_fw,
+            "newer": newer,
+            "download_url": f"{_FW_CDN_BASE}/{model_name}/{model_name}_{latest_fw}.zip",
+        }