feat(claude-desktop): add 3P provider switching with proxy gateway

Adds a new ClaudeDesktop AppType that writes Claude Desktop's third-party
inference profile under configLibrary/, sharing _meta.json with other
launchers (Ollama-compatible) so cc-switch can coexist with them.

Two switch modes:
- direct: provider already exposes claude-* / anthropic/claude-* model
  ids on Anthropic Messages, Claude Desktop connects to it directly.
- proxy: cc-switch's local proxy acts as the inference gateway,
  presenting only claude-* route names to Claude Desktop and mapping
  them to real upstream models. Required after Anthropic restricted
  Claude Desktop to claude-family ids.

Backend:
- New module claude_desktop_config with snapshot/rollback, official seed
  bypass, /claude-desktop/v1/{models,messages} routes, and a single
  source of truth for default proxy routes.
- Gateway token persisted in SQLite, validated on every proxied request.
- get_claude_desktop_status surfaces drift signals (stale models,
  missing routes, proxy stopped, base URL mismatch, missing token).

Frontend:
- Slim ClaudeDesktopProviderForm independent from ProviderForm,
  controlled by a top-level appId guard.
- ProviderList banner consumes the status query (5s polling) and
  renders actionable diagnostics.
- ClaudeDesktopRouteToggle in the header to start/stop the local
  gateway without touching takeover state.
- Three-locale i18n synchronised.

src/hooks/useProxyStatus.ts

@@ -64,6 +64,31 @@ export function useProxyStatus() {
     },
   });
 
+  // 停止服务器（仅停止服务，不改写/恢复其它应用接管状态）
+  const stopProxyServerMutation = useMutation({
+    mutationFn: () => invoke("stop_proxy_server"),
+    onSuccess: () => {
+      toast.success(
+        t("proxy.server.stopped", {
+          defaultValue: "代理服务已停止",
+        }),
+        { closeButton: true },
+      );
+      queryClient.invalidateQueries({ queryKey: ["proxyStatus"] });
+    },
+    onError: (error: Error) => {
+      const detail =
+        extractErrorMessage(error) ||
+        t("common.unknown", { defaultValue: "未知错误" });
+      toast.error(
+        t("proxy.server.stopFailed", {
+          detail,
+          defaultValue: `停止代理服务失败: ${detail}`,
+        }),
+      );
+    },
+  });
+
   // 停止服务器（总开关关闭：强制恢复所有已接管的 Live 配置）
   const stopWithRestoreMutation = useMutation({
     mutationFn: () => invoke("stop_proxy_with_restore"),
@@ -194,6 +219,7 @@ export function useProxyStatus() {
 
     // 启动/停止（总开关）
     startProxyServer: startProxyServerMutation.mutateAsync,
+    stopProxyServer: stopProxyServerMutation.mutateAsync,
     stopWithRestore: stopWithRestoreMutation.mutateAsync,
 
     // 按应用接管开关
@@ -208,9 +234,11 @@ export function useProxyStatus() {
 
     // 加载状态
     isStarting: startProxyServerMutation.isPending,
+    isStoppingServer: stopProxyServerMutation.isPending,
     isStopping: stopWithRestoreMutation.isPending,
     isPending:
       startProxyServerMutation.isPending ||
+      stopProxyServerMutation.isPending ||
       stopWithRestoreMutation.isPending ||
       setTakeoverForAppMutation.isPending,
   };