feat: restore model health check (stream check) UI

Re-enable the stream check feature that was hidden in v3.11.0.
All backend code, database schema, and i18n keys were preserved;
only the frontend UI needed uncommenting across 4 files.
OpenCode and OpenClaw are excluded as the backend does not support them.

src/components/settings/SettingsPage.tsx

@@ -8,6 +8,7 @@ import {
   Cloud,
   ScrollText,
   HardDriveDownload,
+  FlaskConical,
 } from "lucide-react";
 import { toast } from "sonner";
 import {
@@ -38,8 +39,7 @@ import { BackupListSection } from "@/components/settings/BackupListSection";
 import { WebdavSyncSection } from "@/components/settings/WebdavSyncSection";
 import { AboutSection } from "@/components/settings/AboutSection";
 import { ProxyTabContent } from "@/components/settings/ProxyTabContent";
-// Hidden: stream check feature disabled
-// import { ModelTestConfigPanel } from "@/components/usage/ModelTestConfigPanel";
+import { ModelTestConfigPanel } from "@/components/usage/ModelTestConfigPanel";
 import { UsageDashboard } from "@/components/usage/UsageDashboard";
 import { LogConfigPanel } from "@/components/settings/LogConfigPanel";
 import { useSettings } from "@/hooks/useSettings";
@@ -384,6 +384,28 @@ export function SettingsPage({
                         </AccordionContent>
                       </AccordionItem>
 
+                      <AccordionItem
+                        value="test"
+                        className="rounded-xl glass-card overflow-hidden"
+                      >
+                        <AccordionTrigger className="px-6 py-4 hover:no-underline hover:bg-muted/50 data-[state=open]:bg-muted/50">
+                          <div className="flex items-center gap-3">
+                            <FlaskConical className="h-5 w-5 text-emerald-500" />
+                            <div className="text-left">
+                              <h3 className="text-base font-semibold">
+                                {t("modelTest.title")}
+                              </h3>
+                              <p className="text-sm text-muted-foreground font-normal">
+                                {t("modelTest.description")}
+                              </p>
+                            </div>
+                          </div>
+                        </AccordionTrigger>
+                        <AccordionContent className="px-6 pb-6 pt-4 border-t border-border/50">
+                          <ModelTestConfigPanel />
+                        </AccordionContent>
+                      </AccordionItem>
+
                       <AccordionItem
                         value="logConfig"
                         className="rounded-xl glass-card overflow-hidden"