Treat 404 as auth error and persist refreshed tokens

The DKN Cloud NA API returns 404 (not 401) when tokens are expired,
which caused the integration to silently fail with UpdateFailed
indefinitely instead of attempting a token refresh or triggering
reauth. Refreshed tokens were also only held in memory, so they
were lost on Home Assistant restart.

- Add 404 to auth_error_statuses on is_logged_in, refresh_access_token,
  and fetch_installations.
- Persist refreshed access + refresh tokens back to the config entry
  after each successful coordinator update.
- Skip the entry reload listener for token-only option updates to
  avoid a reload loop on every refresh.
- Log API 4xx responses at WARNING with the body so failures are
  visible in HA logs without enabling debug logging.

custom_components/dkncloudna/coordinator.py

@@ -12,7 +12,7 @@ from homeassistant.exceptions import ConfigEntryAuthFailed
 from homeassistant.helpers.update_coordinator import DataUpdateCoordinator, UpdateFailed
 
 from .api import DknAuthError, DknCloudNaClient, DknConnectionError
-from .const import DEFAULT_SCAN_INTERVAL, DOMAIN, LOGGER
+from .const import CONF_REFRESH_TOKEN, CONF_USER_TOKEN, DEFAULT_SCAN_INTERVAL, DOMAIN, LOGGER
 
 
 class DknCoordinator(DataUpdateCoordinator[dict[str, dict[str, Any]]]):
@@ -64,6 +64,8 @@ class DknCoordinator(DataUpdateCoordinator[dict[str, dict[str, Any]]]):
         except Exception as err:  # noqa: BLE001
             raise UpdateFailed(f"Unexpected error: {type(err).__name__}") from err
 
+        self._persist_tokens_if_changed()
+
         devices: dict[str, dict[str, Any]] = {}
         existing = self.data or {}
         for installation in installations or []:
@@ -80,6 +82,25 @@ class DknCoordinator(DataUpdateCoordinator[dict[str, dict[str, Any]]]):
 
         return devices
 
+    def _persist_tokens_if_changed(self) -> None:
+        """Save refreshed tokens back to the config entry so they survive restarts."""
+        opts = self._entry.options
+        stored_token = opts.get(CONF_USER_TOKEN)
+        stored_refresh = opts.get(CONF_REFRESH_TOKEN)
+        if (
+            self.client.token
+            and self.client.refresh_token
+            and (
+                self.client.token != stored_token
+                or self.client.refresh_token != stored_refresh
+            )
+        ):
+            new_opts = dict(opts)
+            new_opts[CONF_USER_TOKEN] = self.client.token
+            new_opts[CONF_REFRESH_TOKEN] = self.client.refresh_token
+            self.hass.config_entries.async_update_entry(self._entry, options=new_opts)
+            LOGGER.debug("DKN tokens persisted after refresh")
+
     async def async_handle_socket_device_data(
         self, mac: str, data: dict[str, Any]
     ) -> None: