UniFi: degrade wan-status & client-ap-traffic to 200 'unavailable' when controller unreachable

Instead of returning HTTP 500 when the UniFi controller can't be reached, these JSON
data feeds now return 200 with an 'available: false' / status 'unavailable' payload so the
dashboard widgets show a friendly unavailable state and the WAN poll stops silently failing.

src/Http/Controllers/StatsController.php

@@ -36,6 +36,7 @@ class StatsController extends Controller
             if ($wanIp && str_starts_with($wanIp, '127.')) $wanIp = $gw['connect_request_ip'] ?? null;
 
             return response()->json([
+                'available' => true,
                 'status'  => $wan['status'] ?? 'unknown',
                 'tx_rate' => $wan['tx_bytes-r'] ?? 0,
                 'rx_rate' => $wan['rx_bytes-r'] ?? 0,
@@ -44,7 +45,19 @@ class StatsController extends Controller
                 'latency' => $wan['latency'] ?? $gw['wan1']['latency'] ?? null,
             ]);
         } catch (\Throwable $e) {
-            return response()->json(['status' => 'error'], 500);
+            // The UniFi controller is unreachable. Degrade gracefully: return 200 with a
+            // friendly "unavailable" payload so the dashboard widget shows an unavailable
+            // state instead of the poll silently failing on a 500.
+            return response()->json([
+                'available' => false,
+                'status'  => 'unavailable',
+                'message' => 'UniFi controller is unreachable.',
+                'tx_rate' => 0,
+                'rx_rate' => 0,
+                'isp'     => null,
+                'wan_ip'  => null,
+                'latency' => null,
+            ]);
         }
     }
 
@@ -296,12 +309,21 @@ class StatsController extends Controller
                 ->values();
 
             return response()->json([
+                'available'  => true,
                 'labels'     => $series['labels'],
                 'traffic_rx' => $rx,
                 'traffic_tx' => $tx,
             ]);
         } catch (\Throwable $e) {
-            return response()->json(['error' => $e->getMessage()], 500);
+            // UniFi controller unreachable — degrade gracefully (200 with empty series)
+            // so the chart shows an empty/unavailable state rather than erroring on a 500.
+            return response()->json([
+                'available'  => false,
+                'message'    => 'UniFi controller is unreachable.',
+                'labels'     => [],
+                'traffic_rx' => [],
+                'traffic_tx' => [],
+            ]);
         }
     }