Implement the conventional MCP pattern for transport backward compatibility:
try `StreamableHTTPClientTransport` first (modern), then fall back to
`SSEClientTransport` (deprecated but needed for older servers).
This follows the approach documented in the MCP TypeScript SDK's
`streamableHttpWithSseFallbackClient.ts` example.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>