feat(mcp): add enabled count to panel info section

- Add enabledCount calculation using useMemo for performance
- Display format: "X MCP server(s) configured · Y enabled"
- Add i18n keys: mcp.enabledCount for zh and en
- Real-time updates when toggling server enabled status

src/components/mcp/McpPanel.tsx

@@ -166,6 +166,11 @@ const McpPanel: React.FC<McpPanelProps> = ({ onClose, onNotify, appType }) => {
     [servers],
   );
 
+  const enabledCount = useMemo(
+    () => serverEntries.filter(([_, server]) => server.enabled).length,
+    [serverEntries],
+  );
+
   const panelTitle =
     appType === "claude" ? t("mcp.claudeTitle") : t("mcp.codexTitle");
 
@@ -205,7 +210,7 @@ const McpPanel: React.FC<McpPanelProps> = ({ onClose, onNotify, appType }) => {
         {/* Info Section */}
         <div className="flex-shrink-0 px-6 pt-4 pb-2">
           <div className="text-sm text-gray-500 dark:text-gray-400">
-            {t("mcp.serverCount", { count: Object.keys(servers).length })}
+            {t("mcp.serverCount", { count: Object.keys(servers).length })} · {t("mcp.enabledCount", { count: enabledCount })}
           </div>
         </div>