The remote MCP endpoint https://mcp.exa.ai/mcp requires API key authentication via x-api-key header. Without this, the connection times out waiting for auth. This change: - Reads EXA_API_KEY from environment variable - Passes it as x-api-key header when available - Updates RemoteMcpConfig type to support optional headers Co-authored-by: Junho Yeo <i@junho.io>