fix(ai): 网络失败时显示友好提示，不再直接展示 Failed to fetch

Co-authored-by: Cursor <cursoragent@cursor.com>

client/src/contexts/DeviceContext.tsx

@@ -10,6 +10,7 @@ import {
   PeqState,
 } from "@/lib/luxsinApi";
 import { getDeviceIpFromUrl, resolveInitialDeviceIp } from "@/lib/deviceIp";
+import { isLikelyNetworkFetchError } from "@/lib/networkError";
 
 interface DeviceContextType {
   ip: string;
@@ -115,7 +116,11 @@ export function DeviceProvider({ children }: { children: React.ReactNode }) {
       setApi(newApi);
       setIsConnected(true);
     } catch (e) {
-      setError(`Connection failed: ${e instanceof Error ? e.message : String(e)}`);
+      setError(
+        isLikelyNetworkFetchError(e)
+          ? null
+          : `Connection failed: ${e instanceof Error ? e.message : String(e)}`,
+      );
       setIsConnected(false);
     } finally {
       setIsConnecting(false);
@@ -151,7 +156,11 @@ export function DeviceProvider({ children }: { children: React.ReactNode }) {
       await fetchState(apiInstance);
       await fetchPeqState(apiInstance).catch(() => undefined);
     } catch (e) {
-      setError(`Refresh failed: ${e instanceof Error ? e.message : String(e)}`);
+      setError(
+        isLikelyNetworkFetchError(e)
+          ? null
+          : `Refresh failed: ${e instanceof Error ? e.message : String(e)}`,
+      );
     }
   }, [api, isConnected, ip, isDemoMode, fetchState, fetchPeqState]);