fix(proxy): resolve 404 error and auto-setup proxy targets

Issues fixed:
1. Route prefix mismatch - Live config was set to use /claude, /codex,
   /gemini prefixes but server only had routes without prefixes
2. Proxy targets not auto-configured - start_with_takeover only modified
   Live config but didn't set is_proxy_target=true for current providers

Changes:
- Add prefixed routes (/claude/v1/messages, /codex/v1/*, /gemini/v1beta/*)
  to server.rs for backward compatibility
- Remove URL prefixes from takeover_live_configs() - server can route
  by API endpoint path alone (/v1/messages=Claude, /v1/chat/completions=Codex)
- Add setup_proxy_targets() method that automatically sets current providers
  as proxy targets when starting proxy with takeover
- Unify proxy toggle in SettingsPage to use takeover mode (same as main UI)
- Fix error message extraction in useProxyStatus hooks
- Fix provider switch logic to check both takeover flag AND proxy running state

src/components/proxy/AutoFailoverConfigPanel.tsx

@@ -18,8 +18,11 @@ export interface AutoFailoverConfigPanelProps {
 
 export function AutoFailoverConfigPanel({
   enabled,
-  onEnabledChange,
+  onEnabledChange: _onEnabledChange,
 }: AutoFailoverConfigPanelProps) {
+  // Note: onEnabledChange is currently unused but kept in the interface
+  // for potential future use by parent components
+  void _onEnabledChange;
   const { t } = useTranslation();
   const { data: config, isLoading, error } = useCircuitBreakerConfig();
   const updateConfig = useUpdateCircuitBreakerConfig();
@@ -262,7 +265,7 @@ export function AutoFailoverConfigPanel({
           </Button>
           <Button
             onClick={handleSave}
-            disabled={updateConfig.isPending || !formData.enabled}
+            disabled={updateConfig.isPending || !enabled}
           >
             {updateConfig.isPending ? (
               <>

src/components/proxy/ProxyToggle.tsx

@@ -0,0 +1,82 @@
+/**
+ * 代理模式切换开关组件
+ *
+ * 放置在主界面头部，用于一键启用/关闭代理模式
+ * 启用时自动接管 Live 配置，关闭时恢复原始配置
+ */
+
+import { Radio, Loader2 } from "lucide-react";
+import { Switch } from "@/components/ui/switch";
+import { useProxyStatus } from "@/hooks/useProxyStatus";
+import { cn } from "@/lib/utils";
+
+interface ProxyToggleProps {
+  className?: string;
+}
+
+export function ProxyToggle({ className }: ProxyToggleProps) {
+  const {
+    isRunning,
+    isTakeoverActive,
+    startWithTakeover,
+    stopWithRestore,
+    isPending,
+    status,
+  } = useProxyStatus();
+
+  const handleToggle = async (checked: boolean) => {
+    if (checked) {
+      await startWithTakeover();
+    } else {
+      await stopWithRestore();
+    }
+  };
+
+  const isActive = isRunning && isTakeoverActive;
+
+  const tooltipText = isActive
+    ? `代理模式运行中 - ${status?.address}:${status?.port}\n切换供应商为热切换`
+    : "开启代理模式\n启用后自动接管 Live 配置";
+
+  return (
+    <div
+      className={cn(
+        "flex items-center gap-2 px-3 py-1.5 rounded-lg transition-all cursor-default",
+        isActive
+          ? "bg-emerald-500/10 border border-emerald-500/30"
+          : "bg-muted/50 hover:bg-muted",
+        className,
+      )}
+      title={tooltipText}
+    >
+      {isPending ? (
+        <Loader2 className="h-4 w-4 animate-spin text-muted-foreground" />
+      ) : (
+        <Radio
+          className={cn(
+            "h-4 w-4 transition-colors",
+            isActive
+              ? "text-emerald-500 animate-pulse"
+              : "text-muted-foreground",
+          )}
+        />
+      )}
+      <span
+        className={cn(
+          "text-sm font-medium transition-colors select-none",
+          isActive
+            ? "text-emerald-600 dark:text-emerald-400"
+            : "text-muted-foreground",
+        )}
+      >
+        Proxy
+      </span>
+      <Switch
+        checked={isActive}
+        onCheckedChange={handleToggle}
+        disabled={isPending}
+        className="ml-1"
+      />
+    </div>
+  );
+}