fix(health-check): disable connectivity check for official providers, restore 6s degraded threshold

Official providers (Claude/Codex/Gemini/Claude Desktop) use OAuth with an intentionally empty base_url and connect via the client's default endpoint, so cc-switch has no reliable reachability target. Probing a guessed endpoint either hits the wrong target or returns a meaningless green light. Hide the connectivity button for category === 'official'; reachability stays available for copilot/codex-oauth/third-party/custom providers, which is where the old real-request probe produced false negatives. Revert the official base_url fallback added earlier — resolve_base_url is back to extract-or-error.

The 1500ms degraded threshold was too strict; normal ~1s probe latencies showed as 'slow'. Restore the original 6000ms scale (default + config panel + per-provider range). Keep the reachability-appropriate 8s timeout / 1 retry.

src/components/providers/ProviderCard.tsx

@@ -548,13 +548,12 @@ export function ProviderCard({
               onEdit={() => onEdit(provider)}
               onDuplicate={() => onDuplicate(provider)}
               onTest={
-                // 连通检测对所有供应商开放（官方会回退到客户端实际会连的官方端点），
-                // 唯独 Claude Desktop 官方除外：它是原生 1P 模式（走 claude.ai，cc-switch
-                // 不在请求路径上），没有可靠的探测目标，故隐藏其检测按钮。
-                onTest &&
-                !(
-                  appId === "claude-desktop" && provider.category === "official"
-                )
+                // 连通检测对第三方/自定义/Copilot/Codex-OAuth 供应商开放（这些正是旧的
+                // 真实请求探测会误报、而可达性探测能正确处理的对象）。官方供应商
+                // (category === "official") 一律隐藏：它们 base_url 故意留空、走客户端
+                // 默认/OAuth 端点，cc-switch 没有可靠的探测目标（尤其 Claude Desktop
+                // 官方是原生 1P 模式，根本不在请求路径上）。
+                onTest && provider.category !== "official"
                   ? () => onTest(provider)
                   : undefined
               }

src/components/providers/forms/ProviderAdvancedConfig.tsx

@@ -144,7 +144,7 @@ export function ProviderAdvancedConfig({
                   id="degraded-threshold"
                   type="number"
                   min={100}
-                  max={10000}
+                  max={60000}
                   value={testConfig.degradedThresholdMs || ""}
                   onChange={(e) =>
                     onTestConfigChange({
@@ -154,7 +154,7 @@ export function ProviderAdvancedConfig({
                         : undefined,
                     })
                   }
-                  placeholder="1500"
+                  placeholder="6000"
                   disabled={!testConfig.enabled}
                 />
               </div>

src/components/usage/ModelTestConfigPanel.tsx

@@ -21,7 +21,7 @@ export function ModelTestConfigPanel() {
   const [config, setConfig] = useState({
     timeoutSecs: "8",
     maxRetries: "1",
-    degradedThresholdMs: "1500",
+    degradedThresholdMs: "6000",
   });
 
   useEffect(() => {
@@ -56,7 +56,7 @@ export function ModelTestConfigPanel() {
       const parsed: StreamCheckConfig = {
         timeoutSecs: parseNum(config.timeoutSecs, 8),
         maxRetries: parseNum(config.maxRetries, 1),
-        degradedThresholdMs: parseNum(config.degradedThresholdMs, 1500),
+        degradedThresholdMs: parseNum(config.degradedThresholdMs, 6000),
       };
       await saveStreamCheckConfig(parsed);
       toast.success(t("streamCheck.configSaved"), {
@@ -137,9 +137,9 @@ export function ModelTestConfigPanel() {
             <Input
               id="degradedThresholdMs"
               type="number"
-              min={200}
-              max={10000}
-              step={100}
+              min={1000}
+              max={30000}
+              step={1000}
               value={config.degradedThresholdMs}
               onChange={(e) =>
                 setConfig({ ...config, degradedThresholdMs: e.target.value })