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/useProviderActions.ts

@@ -171,6 +171,13 @@ export function useProviderActions(
           proxyRequiredReason = t("notifications.proxyReasonOpenAIResponses", {
             defaultValue: "使用 OpenAI Responses 接口格式",
           });
+        } else if (
+          activeApp === "claude-desktop" &&
+          provider.meta?.claudeDesktopMode === "proxy"
+        ) {
+          proxyRequiredReason = t("notifications.proxyReasonClaudeDesktop", {
+            defaultValue: "使用 Claude Desktop 本地路由模式",
+          });
         } else if (
           provider.meta?.isFullUrl &&
           (activeApp === "claude" || activeApp === "codex")
@@ -223,12 +230,22 @@ export function useProviderActions(
           // OpenCode/OpenClaw: show "added to config" message instead of "switched"
           const isMultiProviderApp =
             activeApp === "opencode" || activeApp === "openclaw";
-          const messageKey = isMultiProviderApp
-            ? "notifications.addToConfigSuccess"
-            : "notifications.switchSuccess";
-          const defaultMessage = isMultiProviderApp
-            ? "已添加到配置"
-            : "切换成功！";
+          const messageKey =
+            activeApp === "claude-desktop"
+              ? provider.meta?.claudeDesktopMode === "proxy"
+                ? "notifications.claudeDesktopProxyRestartRequired"
+                : "notifications.claudeDesktopRestartRequired"
+              : isMultiProviderApp
+                ? "notifications.addToConfigSuccess"
+                : "notifications.switchSuccess";
+          const defaultMessage =
+            activeApp === "claude-desktop"
+              ? provider.meta?.claudeDesktopMode === "proxy"
+                ? "切换成功，请保持 CC Switch 运行，并重启 Claude Desktop 后生效"
+                : "切换成功，重启 Claude Desktop 后生效"
+              : isMultiProviderApp
+                ? "已添加到配置"
+                : "切换成功！";
 
           toast.success(t(messageKey, { defaultValue: defaultMessage }), {
             closeButton: true,