feat: classify stream check errors with color-coded toasts

Distinguish between "provider rejects probe" (yellow warning) and
"genuinely broken" (red error) in health check results.

Backend: add AppError::HttpStatus variant to carry structured HTTP
status codes, populate http_status on error results, classify codes
into short labels (e.g. "Auth rejected (401)"), and truncate overly
long response bodies.

Frontend: route 401/403/400/429/5xx to toast.warning with localized
hints explaining the error may not indicate actual unusability; route
404/402/connection errors to toast.error. Add i18n keys for all three
locales (zh/en/ja).

Also deduplicate check_once by reusing build_stream_check_result.

src/components/providers/forms/ProviderAdvancedConfig.tsx

@@ -1,11 +1,6 @@
 import { useTranslation } from "react-i18next";
 import { useState, useEffect } from "react";
-import {
-  ChevronDown,
-  ChevronRight,
-  FlaskConical,
-  Coins,
-} from "lucide-react";
+import { ChevronDown, ChevronRight, FlaskConical, Coins } from "lucide-react";
 import { Input } from "@/components/ui/input";
 import { Label } from "@/components/ui/label";
 import { Switch } from "@/components/ui/switch";

src/hooks/useStreamCheck.ts

@@ -47,13 +47,37 @@ export function useStreamCheck(appId: AppId) {
           // 降级状态也重置熔断器，因为至少能通信
           resetCircuitBreaker.mutate({ providerId, appType: appId });
         } else {
-          toast.error(
-            t("streamCheck.failed", {
-              providerName: providerName,
-              message: result.message,
-              defaultValue: `${providerName} 检查失败: ${result.message}`,
-            }),
-          );
+          const httpStatus = result.httpStatus;
+          const hintKey = httpStatus
+            ? `streamCheck.httpHint.${httpStatus >= 500 ? "5xx" : httpStatus}`
+            : null;
+          const description =
+            (hintKey ? t(hintKey, { defaultValue: "" }) : "") || undefined;
+
+          // 401/403/400 = 检查被拒（供应商可能正常）；429/5xx = 临时问题
+          const isProbeRejection =
+            httpStatus != null &&
+            ([401, 403, 400, 429].includes(httpStatus) || httpStatus >= 500);
+
+          if (isProbeRejection) {
+            toast.warning(
+              t("streamCheck.rejected", {
+                providerName: providerName,
+                message: result.message,
+                defaultValue: `${providerName} 检查被拒: ${result.message}`,
+              }),
+              { description, duration: 8000, closeButton: true },
+            );
+          } else {
+            toast.error(
+              t("streamCheck.failed", {
+                providerName: providerName,
+                message: result.message,
+                defaultValue: `${providerName} 检查失败: ${result.message}`,
+              }),
+              { description, duration: 8000, closeButton: true },
+            );
+          }
         }
 
         return result;

src/i18n/locales/en.json

@@ -2129,7 +2129,17 @@
     "operational": "{{providerName}} is operational ({{responseTimeMs}}ms)",
     "degraded": "{{providerName}} is slow ({{responseTimeMs}}ms)",
     "failed": "{{providerName}} check failed: {{message}}",
-    "error": "{{providerName}} check error: {{error}}"
+    "rejected": "{{providerName}} check rejected: {{message}}",
+    "error": "{{providerName}} check error: {{error}}",
+    "httpHint": {
+      "400": "Provider rejected request format. Health check probe may differ from actual usage.",
+      "401": "API key may be invalid, or provider uses OAuth auth. Check failure doesn't mean it's unusable.",
+      "402": "Account quota or billing issue.",
+      "403": "Provider blocked this request. Some verify client identity; may work fine in actual use.",
+      "404": "Endpoint not found. Check base URL and API path.",
+      "429": "Too many requests. Try again later.",
+      "5xx": "Provider internal error. Likely temporary."
+    }
   },
   "proxyConfig": {
     "proxyEnabled": "Routing Master Switch",

src/i18n/locales/ja.json

@@ -2129,7 +2129,17 @@
     "operational": "{{providerName}} は正常に動作しています ({{responseTimeMs}}ms)",
     "degraded": "{{providerName}} の応答が遅いです ({{responseTimeMs}}ms)",
     "failed": "{{providerName}} のチェックに失敗しました: {{message}}",
-    "error": "{{providerName}} のチェックでエラーが発生しました: {{error}}"
+    "rejected": "{{providerName}} のチェックが拒否されました: {{message}}",
+    "error": "{{providerName}} のチェックでエラーが発生しました: {{error}}",
+    "httpHint": {
+      "400": "リクエスト形式が拒否されました。ヘルスチェックの形式は実際の使用と異なる場合があります。",
+      "401": "APIキーが無効か、OAuthなどの認証方式を使用しています。チェック失敗は実際に使えないことを意味しません。",
+      "402": "アカウントの利用枠または請求の問題です。",
+      "403": "プロバイダーがリクエストを拒否しました。実際の使用では正常に動作する場合があります。",
+      "404": "エンドポイントが見つかりません。Base URLとAPIパスを確認してください。",
+      "429": "リクエストが多すぎます。しばらくしてからお試しください。",
+      "5xx": "プロバイダーの内部エラーです。一時的な問題の可能性が高いです。"
+    }
   },
   "proxyConfig": {
     "proxyEnabled": "ルーティング総スイッチ",

src/i18n/locales/zh.json

@@ -2130,7 +2130,17 @@
     "operational": "{{providerName}} 运行正常 ({{responseTimeMs}}ms)",
     "degraded": "{{providerName}} 响应较慢 ({{responseTimeMs}}ms)",
     "failed": "{{providerName}} 检查失败: {{message}}",
-    "error": "{{providerName}} 检查出错: {{error}}"
+    "rejected": "{{providerName}} 检查被拒: {{message}}",
+    "error": "{{providerName}} 检查出错: {{error}}",
+    "httpHint": {
+      "400": "供应商拒绝了请求格式。健康检查的探测格式可能与实际使用不同。",
+      "401": "API Key 可能无效，或供应商使用 OAuth 等认证方式。检查失败不代表实际不可用。",
+      "402": "账户配额或计费问题。",
+      "403": "供应商拒绝了此请求。部分供应商会校验客户端身份，检查失败但实际使用可能正常。",
+      "404": "接口地址不存在，请检查 Base URL 和 API 路径。",
+      "429": "请求频率过高，请稍后重试。",
+      "5xx": "供应商内部错误，通常是临时问题。"
+    }
   },
   "proxyConfig": {
     "proxyEnabled": "路由总开关",