feat(mcp): add OAuth2ConnectButton for per-row PKCE connect flow

ui/litellm-dashboard/src/components/mcp_tools/OAuth2ConnectButton.tsx

@@ -0,0 +1,62 @@
+"use client";
+
+import React, { useCallback } from "react";
+import { CheckOutlined } from "@ant-design/icons";
+import { useUserMcpOAuthFlow } from "@/hooks/useUserMcpOAuthFlow";
+import { MCPServer } from "./types";
+
+interface OAuth2ConnectButtonProps {
+  server: MCPServer;
+  accessToken: string;
+  onSuccess: () => void;
+}
+
+/**
+ * Renders the appropriate credential UI for an OAuth2 MCP server in the catalog table:
+ *   - Not connected → blue "Connect" button (starts PKCE redirect flow)
+ *   - Connected + internal user → green badge + "Disconnect" link
+ *   - Connected + admin → green badge + "Reconnect" link
+ */
+const OAuth2ConnectButton: React.FC<OAuth2ConnectButtonProps> = ({
+  server,
+  accessToken,
+  onSuccess,
+}) => {
+  const { startOAuthFlow, status } = useUserMcpOAuthFlow({
+    accessToken,
+    serverId: server.server_id,
+    serverAlias: server.server_name ?? server.alias ?? undefined,
+    onSuccess,
+  });
+
+  const loading = status === "authorizing" || status === "exchanging";
+
+  if (server.has_user_credential) {
+    return (
+      <div className="flex items-center gap-2">
+        <span className="inline-flex items-center gap-1 text-xs font-medium px-2 py-0.5 rounded-full bg-green-50 text-green-700 border border-green-200">
+          <CheckOutlined style={{ fontSize: 10 }} /> Connected
+        </span>
+        <button
+          className="text-xs text-gray-400 hover:text-blue-600 transition-colors"
+          onClick={startOAuthFlow}
+          disabled={loading}
+        >
+          Reconnect
+        </button>
+      </div>
+    );
+  }
+
+  return (
+    <button
+      className="text-xs bg-blue-600 hover:bg-blue-700 disabled:bg-blue-300 text-white px-3 py-1 rounded-md font-medium transition-colors shadow-sm"
+      onClick={startOAuthFlow}
+      disabled={loading}
+    >
+      {loading ? "Connecting…" : "Connect"}
+    </button>
+  );
+};
+
+export default OAuth2ConnectButton;