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/components/proxy/ClaudeDesktopRouteToggle.tsx

@@ -0,0 +1,96 @@
+import { Loader2, Radio } from "lucide-react";
+import { toast } from "sonner";
+import { useTranslation } from "react-i18next";
+import { Switch } from "@/components/ui/switch";
+import { useProxyStatus } from "@/hooks/useProxyStatus";
+import { cn } from "@/lib/utils";
+
+interface ClaudeDesktopRouteToggleProps {
+  className?: string;
+}
+
+export function ClaudeDesktopRouteToggle({
+  className,
+}: ClaudeDesktopRouteToggleProps) {
+  const { t } = useTranslation();
+  const {
+    isRunning,
+    status,
+    takeoverStatus,
+    startProxyServer,
+    stopProxyServer,
+    isStarting,
+    isStoppingServer,
+  } = useProxyStatus();
+
+  const isBusy = isStarting || isStoppingServer;
+  const otherTakeoverActive = Boolean(
+    takeoverStatus?.claude || takeoverStatus?.codex || takeoverStatus?.gemini,
+  );
+  const routeAddress = status?.address ?? "127.0.0.1";
+  const routePort = status?.port ?? 15721;
+
+  const handleToggle = async (checked: boolean) => {
+    try {
+      if (checked) {
+        await startProxyServer();
+        return;
+      }
+
+      if (otherTakeoverActive) {
+        toast.warning(
+          t("claudeDesktop.route.stopBlockedByTakeover", {
+            defaultValue:
+              "其它应用正在使用代理接管。请先在设置中关闭对应应用接管，再停止本地路由。",
+          }),
+          { duration: 5000 },
+        );
+        return;
+      }
+
+      await stopProxyServer();
+    } catch (error) {
+      console.error("[ClaudeDesktopRouteToggle] Toggle route failed:", error);
+    }
+  };
+
+  const tooltipText = isRunning
+    ? t("claudeDesktop.route.tooltip.active", {
+        address: routeAddress,
+        port: routePort,
+        defaultValue: `Claude Desktop 本地路由已开启 - ${routeAddress}:${routePort}`,
+      })
+    : t("claudeDesktop.route.tooltip.inactive", {
+        address: routeAddress,
+        port: routePort,
+        defaultValue: `开启 Claude Desktop 本地路由，用于需要模型映射或格式转换的供应商。当前配置地址：${routeAddress}:${routePort}`,
+      });
+
+  return (
+    <div
+      className={cn(
+        "flex items-center gap-1 px-1.5 h-8 rounded-lg bg-muted/50 transition-all",
+        className,
+      )}
+      title={tooltipText}
+    >
+      {isBusy ? (
+        <Loader2 className="h-4 w-4 animate-spin text-muted-foreground" />
+      ) : (
+        <Radio
+          className={cn(
+            "h-4 w-4 transition-colors",
+            isRunning
+              ? "text-emerald-500 animate-pulse"
+              : "text-muted-foreground",
+          )}
+        />
+      )}
+      <Switch
+        checked={isRunning}
+        onCheckedChange={handleToggle}
+        disabled={isBusy}
+      />
+    </div>
+  );
+}